Well there we are: quite a day, with a result that has set off conspiracy theories on both sides. In its next term the supreme court will probably have to rule on same-sex marriage and who knows what else.

We'll be back tomorrow with more coverage of the fallout. But for now, Obamacare remains the law of the land.

In the meantime, here's Mitt Romney explaining why the individual mandate is such a great idea – in 2006. Let's assume he's not so pleased with that development tonight.

Here's a summary of what happened today as the US supreme court voted to uphold the constitutionality of the Affordable Care Act:

• The supreme court voted 5-4 to uphold the individual mandate – the central core of Barack Obama's programme healthcare reforms

• Chief Justice John Roberts surprised conservatives by joining the court's liberal wing in backing the law, redefining the mandate as a tax rather than an exercise under the constitution's commerce clause

• Anthony Kennedy – thought to be the court's key swing vote – joined the minority and voted with Antonin Scalia, Clarence Thomas and Samuel Alito to void the law

• The court ruled that the commerce clause failed to justify compulsory insurance purchase, arguing that the state could not penalise inactivity

• The government's plan to strip states of healthcare funding if they opted out of the law's Medicaid expansion was declared unconstitutional, creating a new limit on federal power

• Barack Obama greeted the decision as a victory for the American people "whose lives are more secure because of this law"

• Republican presidential candidate Mitt Romney repeated his opposition to the healthcare reforms and declared: "I will act to repeal Obamacare"

• The Romney campaign claimed to have raised more than $2.5m in online donations during the hours following the ruling

And possibly the best single-article summary of the legal ins and outs of today's supreme court ruling is from Professor Timothy Jost, a healthcare specialist and a professor of law at the Washington and Lee University.

The Los Angeles Times has edited highlights of the court's majority opinion, including this passage by Chief Justice John Roberts on abuse of the commerce clause:

Indeed, the Government's logic would justify a manda­tory purchase to solve almost any problem.… To consider a different example in the health care market, many Americans do not eat a balanced diet. That group makes up a larger percentage of the total population than those without health insurance. Those in­creased costs are borne in part by other Americans who must pay more, just as the uninsured shift costs to the insured. Congress addressed the insurance problem by ordering everyone to buy insurance. Under the Government's theory, Congress could address the diet problem by ordering everyone to buy vegetables.

Vegetables? I'll give you my hotdog when you pry it from my cold, mustard-stained hands.

This photo is from yesterday but it actually sums up today for Nancy Pelosi and John Boehner respectively.

Delightful stuff from Pablo Martinez Monsivais of the Associated Press.

The National Journal's wise Ron Brownstein says the supreme court decision to allow states to opt out of the Medicaid expansion will heighten the political arguments over healthcare:

While upholding the individual mandate at the law's core, the five-member majority led by Chief Justice John Roberts struck down one aspect of the law's expansion of Medicaid, the joint federal-state program providing health insurance for the poor. In so doing the Court virtually guaranteed sharper debate in the states, especially Republican-leaning red states, over whether to join the program the law establishes to expand Medicaid eligibility and coverage. Those decisions will carry substantial stakes. Many of the conservative states most likely to opt out of the Medicaid expansion are also among the states with the largest number of uninsured. National Journal has calculated that the 26 states that joined the lawsuit against the Medicaid expansion contain 27.6 million uninsured, a 55% majority of all the uninsured in America, according to Census Bureau figures. That includes Texas at 6.1 million uninsured, Florida at 3.9 million, and Georgia at 1.9 million.

Brownstein does say that state governors who reject the Medicaid expansion pay-out will be making "a starkly ideological decision. But that doesn't mean that some of the governors who joined the lawsuit against the reform plan won't do exactly that."

President Obama learned about the healthcare ruling the same – wrong – way as everyone else by watching CNN and Fox News:

President Obama was just outside the Oval Office Thursday morning when he got the news – erroneous, as it turned out – that the US Supreme Court had struck down the individual mandate in his signature health care law, deeming it unconstitutional. Standing with White House chief of staff Jack Lew and looking at a television in the "Outer Oval" featuring a split screen of four different networks, the president saw graphics on the screens of the first two cable news networks to break the news – CNN and Fox News Channel – announcing, wrongly, that he had lost. Senior administration officials say the president was calm. A couple minutes later, White House counsel Kathy Ruemmler came to Outer Oval and gave him two thumbs-up. Ruemmler had gotten the correct information from a White House lawyer at the Supreme Court and from ScotusBlog.com.

Boo for old media CNN and Fox News. Yay for new media bloggy types.

Republicans are in a state of shock after today's healthcare ruling, stunned at a decision that they were confident of winning and feeling betrayed by their previous poster boy John Roberts.

But Indiana congressman Mike Pence went overboard, reports Politico:

In a closed door House GOP meeting Thursday, Indiana congressman and gubernatorial candidate Mike Pence likened the Supreme Court's ruling upholding the Democratic health care law to the September 11 terrorist attacks, according to several sources present. He immediately apologized. "My remarks at the Republican Conference following the Supreme Court decision were thoughtless. I certainly did not intend to minimize any tragedy our nation has faced and I apologize," Pence said in a statement to Politico.

I'm sure no one will remember that when Pence runs to be governor of Indiana, as he's reputed to be planning. Or was.

So it turns out that Barack Obama's signature piece of legislation was rescued for him by Chief Justice John Roberts, notes Jamie Dupree:

It was a supremely ironic outcome, as the Roberts Court has been heavily criticized by Democrats in the Congress and the White House in recent years – in fact, go back to 2005 when the Chief Justice's nomination was up before the Senate, and you will find Senators named Obama and Biden were two of the 22 votes against. Today though, the Chief Justice delivered the President a major political victory.

The Guardian's Karen McVeigh talks to Ben Munoz, a medical student and patient advocate from Texas, who welcomes the supreme court ruling after his own battle with debilitating illness:

Munoz's life and his previously conservative mindset over the role of government in healthcare altered dramatically six years ago after suffering a life-threatening stroke caused by a rare brain condition. "Here in Texas, there's a lot of anti-government feeling, that it should stay out of healthcare" said Munoz, 35, who also runs a network of patient communities for people affected by a rare disease. "I thought that the government doesn't have much of a role to play in this. But when you experience the threat of bankruptcy because of an illness, when you feel that pain, your feelings change." Munoz has now fully recovered from the stroke he suffered while he was studying for an MBA at Northwestern University in Chicago. Caused by a rare condition, arterio venous malformation, it came out of the blue and Munoz had to undergo two years of gruelling treatment, including neurosurgery and extensive radiotherapy. Munoz said he was relieved that the ACA had been passed because it included provisions that those who suffer rare illnesses had fought for. Two of the biggest, said Munoz, were that insurance companies have to cover pre-existing conditions and that they can no longer include lifetime insurance caps. "This was a big one, because for our community, even if you have insurance, the thought that it can be capped is very frightening for people. Mine was $100,000 for one year but I have a friend whose costs were $200,000. We had good insurance but they could have capped it." The pre-existing condition stipulation was also very important, he said. "A member of our community was looking for help recently because she was no longer eligible for insurance. She had a facial nerve condition which was a chronic condition. But she lost her job and she lost her healthcare. She could not get insurance because it was a pre-existing condition and she was reaching out to her network to try and find something." "Rare conditions are often genetic and they are often chronic. People worry about whether their job comes with health insurance. It's very restricting on what they do for a living. The thought that healthcare costs can be capped is also very frightening for my patients." Munoz welcomed two provisions which patients with rare illnesses had fought for: that insurers could no longer stop coverage for people with dire diagnosis and a public health insurance option so that everyone could afford it.

Feel some sympathy towards the number-crunchers, boffins and wonks at the Congressional Budget Office:

CBO is in the process of reviewing the Supreme Court's decision related to the Affordable Care Act to assess the effect on CBO's projections of federal spending and revenue under current law. We expect that this assessment will probably take some time.

You can almost hear a quiet sob of desperation in that last sentence.

Which states will be most affected by today's ruling? The Atlantic has a quick run-down:

More than one in five people are uninsured in roughly a dozen states, starting with Texas (27.6%), Mississippi (23.5%), Florida (22.9%), Oklahoma (22.1%), California (22%), and Nevada (21.9%).

Interestingly, Texas, Florida and Mississippi are among the states most likely to grandstand over the Medicaid expansion, at least in the short term. Texas and Florida are respectively the second and third largest states in the union.

The Democratic attack dogs are out on the prowl, with Bill Burton of the Priorities USA super pac emailing out a statement that Mitt Romney's claims on health care are "intentionally dishonest and two-faced":

In Massachusetts, Romney imposed a penalty for not purchasing insurance that is twice as large as the federal law that he now attacks. According to Democrats, Republicans and Romney himself, the Massachusetts law was the model for national health insurance reform. Romney's attacks on health care reform he previously supported show the American people that he is a dishonest politician who will say anything to win an election.

The Guardian's Chris McGreal is talking to healthcare experts on the impact of today's ruling, and in particular the possibility of states opting out of the Medicaid expansion:

John Culhane, director of the Health Law Institute at Widener university, said that he doubts many states will opt out of the expanded Medicaid coverage even if they are ideologically opposed to the health reform law because it will not be in their financial interests. Under the legislation, the federal governments pays the entire cost of the expansion of Medicaid coverage for the first few years. That eventually drops to 90% but the states will never have to pick up more than a fraction of the real costs whereas they already often have to cover the expense of uninsured people who walk into the emergency rooms of public hospitals and receive coverage without paying the bills. "The states would be crazy in my opinion not to take it," said Culhane. "If the Feds are giving you all of this money why would you turn this down? You would have deeply political reasons and really hate this legislation. Maybe one or two deep southern states might do this but I would be willing to bet that most will not.

Hmm: "deeply political reasons and really hate this legislation" – that doesn't describe the GOP anywhere, does it? But otherwise, that's good news for the uninsured poor.

Nate Silver, psephologist to the New York Times, warns against the idea that today's ruling is a boost to Mitt Romney's election chances:

[C]ontinued dissatisfaction over the health care bill was presumably already priced into the polls. A decision that upholds the status quo is not likely to change that much. To the extent there are marginal effects of the court's decision, they would seem to be positive for Mr Obama. The framework of the bill has now been endorsed by the court, including by John Roberts, the relatively conservative and relatively well-respected Chief Justice who wrote the majority opinion.

It is a major loss when a Pres pushes law that is declared unconst. Having the law affirmed = win. In that respect, this is a win for Obama — CookPoliticalReport (@CookPolitical) June 28, 2012

Political analyst Charlie Cook appears to agree.

Lyle Dennison of ScotusBlog thinks that the new-look individual mandate tax might not be as successful as the original version:

Since President Obama signed the new law, it has been understood by almost everyone that the expansion of health care coverage to tens of millions of Americans without it could work — economically — only if the health insurance companies were guaranteed a large pool of customers. The mandate to buy health insurance by 2014 was the method Congress chose to supply that pool. It is not immediately clear whether the Court's approach will produce as large a pool of new customers. The ACA's key provision now amounts to an invitation to buy insurance, rather than an order to do so, with a not-very-big tax penalty for going without.

CNN thought it would be useful to record Hillary Clinton's reaction to the supreme court's ruling as she was stepping off a plane in Russia:

You know, I haven't had the chance to read the decision. I literally just heard as we landed that the Supreme Court has upheld the health care law.

Ok then. To be fair to Clinton and to CNN she went on to say "Obviously I want to get into the details, but I'm very pleased."

It's not been a good day for CNN, which has issued this contrite note after prematurely announcing that the individual mandate had been struck down:

In his opinion, Chief Justice Roberts initially said that the individual mandate was not a valid exercise of Congressional power under the Commerce Clause. CNN reported that fact, but then wrongly reported that therefore the court struck down the mandate as unconstitutional. However, that was not the whole of the Court's ruling. CNN regrets that it didn't wait to report out the full and complete opinion regarding the mandate. We made a correction within a few minutes and apologize for the error.

Fox News did the same, but they are all, whatever.

What will be the impact of the court's decision to allow states to painlessly opt out of the Medicaid expansion? The always readable Josh Barro says it's not a big deal:

Some people are fretting about this. They worry that states will opt out and low-income people in conservative states will be left without coverage. But I think we will have expanded Medicaid in all 50 states in pretty short order. The health care law had both a carrot and a stick to encourage states to expand Medicaid eligibility. The stick was the potential loss of all federal Medicaid funds if they didn't. The carrot was that the federal government will pay for nearly the entire cost of Medicaid expansion – 100% of it in the early years, gradually declining to 90%. That's a pretty big carrot. States that refuse to expand Medicaid will be rejecting nearly free federal money. Such a rejection would be tantamount to saying that government health insurance for low-income people is so undesirable that a state is not even willing to pay ten cents on the dollar for it.

Barro blames Republican grandstanding for this even being an issue, and if he's right then it is good news.

On the other hand, I wouldn't underestimate the ability of some states – Texas, Florida – to cut off their nose to spite their face if it also spites Obamacare. Florida in particular. There are states, after all, that rejected federal stimulus funds, including Florida. The CBO also estimated the Medicaid expansion as costing states $20bn until 2019 – not a huge amount in the scheme of things but not nothing for larger states, and enough of a fig leaf for Republicans to claim a fiscal case for opting out.

Still, if Barro is right and the carrot is so big that even the most ideological GOP governors can't refuse it eventually, then the expansion will go ahead relatively smoothly.

Despite the blather from the likes of Michele Bachmann earlier today, the majority opinion today actually appears to curtail the federal government's powers under the commerce clause of the constitution:

The individual mandate, however, does not regulate existing commercial activity. It instead compels individuals to become active in commerce by purchasing a product,on the ground that their failure to do so affects interstate commerce. Construing the Commerce Clause to permit Congress to regulate individuals precisely because they are doing nothing would open a new and potentially vast domain to congressional authority. Every day individuals do not do an infinite number of things. In some cases they decide not to do something; in others they simply fail to do it. Allowing Congress to justify federal regulation by pointing to the effect of inaction on commerce would bring countless decisions an individual could potentially make within the scope of federal regulation, and – under the Government's theory – empower Congress to make those decisions for him.

Or her, John Roberts. So I think we can conclude that the supreme court would not uphold a congressional mandate for everyone to purchase broccoli.

Back to Florida – the state that triggered the challenge that the supreme court ruled on this morning – where the Guardian's Richard Luscombe reveals the political fallout in the Sunshine State:

In Florida, the state that was the lead plaintiff in the lawsuit against Obamacare, attorney general Pam Bondi may soon be applying for a refund on her crystal ball. Because just two days ago, in an interview with Fox News, she maintained that the Supreme Court was clearly aligning in her direction, based on her observations of the justices during an oral testimony session at which she was present earlier this year. "The main questions that they asked made me feel very confident that they saw our point of view, that they took this very seriously and that they realised this would be the greatest over-reach of federal power in our entire history if this act is upheld," she said in Tuesday's interview. Bondi had stood to reap significant political and personal prestige had the lawsuit succeeded. The Republican National Convention is heading to her hometown of Tampa, Florida, in just over eight weeks time, offering her a stage on which the party had looked set to parade her as a hero. The lawsuit against Obamacare was filed in March 2010 by Florida's then attorney-general, Republican Bill McCollum, within minutes of the president having signed the act into law. With Florida leading the charge, 25 other states joined the legal challenge, which was spearheaded after McCollum's departure from office in January 2010 by Bondi, his successor.

Bondi may still be able to claim some sort of victory, now that Florida can opt out of the Medicaid expansion without penalty after today's supreme court ruling. And that is presumably what it will do.

Here's a copy of the supreme court decision.

If that doesn't work, there's a pdf version here.

Nancy Pelosi is next up, speaking to journalists at the Capitol, and she looks pretty pleased.

"Being a woman will no longer be a pre-existing condition," says Pelosi, noting all the benefits of the law. "It's pretty exciting."

For the record, Pelosi always maintained that the law would be upheld by the supreme court. Pelosi was an influential figure during the chaos around passing the law in 2009 and 2010.

"For the American people, the best is yet to come," says Pelosi, who mentions her call today to Ted Kennedy's family.

"I knew that when he left us I knew he would go to heaven and help pass the bill," says Pelosi. "And now he can rest in peace. His dream of healthcare reform for America's families has become a reality."

Asked about quibbles over the court's definition of the mandate as a tax, Pelosi says pointedly: "Take yes for an answer."

The Guardian's Richard Luscombe is in Florida talking to people affected by today's decision:

Mark Freher, a Florida heart doctor, mostly welcomed the decision and believes that as a result the healthcare industry is "heading in the right direction". "A lot of it is political," says Freher, a specialist in cardio-electrophysiology who sees up to 200 patients a month at the JFK Medical Centre in West Palm Beach, mostly working with those who need pacemakers and defibrillators. "It's getting people insurance without figuring out a way to pay for it." But he believes that ensuring everybody has affordable health insurance will help to fix a system he sees as full of disparity. "If you're 90 and insured, we'll make you better, but if you're 30 and uninsured you're left to the wolves," he says. "Obamacare does more for the wider population. For people that have money, it doesn't matter but it's a crap shoot if you're poor and get sick." Freher says five to 10 per cent of his patients currently are uninsured, and are treated for free. "I feel the need," he says. He said he also welcomes the provision allowing children to stay on their parents' policies until the age of 26 as a no-brainer: "Kids on $8 an hour can't afford healthcare." If everyone is to have a policy, he says, healthcare insurance industry could also use more than a little tweaking itself. "Insurance companies have done a poor job what they were supposed to do, spreading risk over a wide area," he says. "They've just become bill collectors and bill payers." He says he does have some issues with some of the consequences of the Obama's health reforms, especially the Medicaid provisions. Since the law passed, he says, he is spending "an hour to an hour and a half more each day" on medical records and forms. "If the issue is we have to get more efficient in the use of our resources then I'm not sure that addresses it," he says. But Freher thinks the reforms will stand after the Supreme Court ruling. "I doubt the Republicans will come in and get rid of it," he says. "It's easier to fix things than start afresh."

"The highest court in the land has now spoken. We will continue to implement this law," says Obama, looking fairly pleased with that decision. "But what the country can't afford to do is re-fight the political battles of two years ago."

That's an interesting reposte to Romney's angry demand to replace the law – and one that appeals to those wanting a quieter political life.

"Now is the time to focus on the biggest challenge of our time," Obama continues, that being the economy. But he concludes:

Today I am as confidence as ever, that when we look back five years from now, or 10 years from now, or 20 years from now, we will be better off because we had the courage to pass this law and keep moving forward.

And that's it, no time for questions.

What was interesting is that Obama – for the first time in a while – offered an unapologetic defence of the healthcare reforms. That's going to make for a different approach in the presidential campaign.

Obama says: "It should be pretty clear by now that I didn't do this because it would be good politics." You can say that again.

And on time for a change, here's President Obama speaking from the White House.

"Whatever the politics, today's decision was a victory for people all over this country," says Obama, who is going to take this as an opportunity to talk up his healthcare reforms. Could this change public perceptions?

Obama runs through the various benefits of the law, including the ban on pre-existing conditions, the extension of parental health insurance to children aged under 26 and so on.

Mitt Romney is now speaking, and vows: "What the court did not do in its last day of session, I will do on my first day as president."

While the supreme court upheld the law, "what they did not do is say that Obamacare is good law or good policy," Romney says.

"Our mission is clear: if we want to replace Obamacare, we have to replace President Obama," says Romney. It's all about jobs.

"Help us defeat Obamacare, help us defeat the liberal agenda," says the man who forced the individual mandate on the people of Massachusetts.

Tough talking by Romney but no detail on what he would do, other than platitudes. But then he's only a presidential candidate. Tub-thumping despite presumably being calibrated to appeal to swing state independents, Romney sounded more wound-up than presidential.

This reveals that today's decision isn't as good for Romney as the alternative in which the court threw the law out. Complaining about supreme decisions is a little like complaining about the referee. No wonder Romney is looking a bit sad puppy.

It's short and, well not sweet. Romney leaves, ignoring questions shouted at him by rude journalists.

Back to the landmine hidden inside the supreme court ruling and the ability of states to opt out of the Medicaid expansion.

The Congressional Budget Office estimates that the expansion would have increased Medicaid/CHIP coverage by 16 million people from a baseline of 35 million by 2019 – with a cost to the federal government of $434bn from 2010 to 2019 because of the expanded coverage.

The CBO estimated that the expansion would increase state spending over baseline spending by $20bn during 2010-2019 – and it's that $20bn that is the core of the states' objections to accepting the Medicaid expansion.

Nancy Pelosi – the Democrat leader in the House when healthcare reform was passed – has a celestial reaction to the supreme court ruling:

Nancy Pelosi called Vicki Kennedy following SCOTUS ruling and said "Now, Teddy can rest." — Susan Davis (@DaviSusan) June 28, 2012

That's ... unusual.

ScotusBlog has a long explanation of how the Medicaid expansion decision came about – and specifically, how liberal lions Breyer and Kagan voted to allow states to opt out of the Affordable Care Act's Medicaid expansion:

The Court's decision on the constitutionality of the Medicaid expansion is divided and complicated. The bottom line is that: (1) Congress acted constitutionally in offering states funds to expand coverage to millions of new individuals; (2) So states can agree to expand coverage in exchange for those new funds; (3) If the state accepts the expansion funds, it must obey by the new rules and expand coverage; (4) but a state can refuse to participate in the expansion without losing all of its Medicaid funds; instead the state will have the option of continue the its current, unexpanded plan as is.

The net result: a proportion of the 16 million people who would have healthcare extended to them as Medicaid will now not receive it. How many? Someone needs to crunch some numbers.

The Guardian's Dominic Rushe reports on the reaction on Wall Street, happy to profit from people's misery:

The Dow has dropped 155 points (1.22%) following the Scotus ruling but that's probably more to do with news from Europe – or the lack of it – than Obamacare. There is some fallout for the healthcare industry though. Hospital stocks have soared. Hospitals have been rooting for the law to stay – more Americans with health cover means more patients. HCA Holdings was up 8.5% and THC Healthcare rose 11%. What's the opposite of ambulance chasers?

The news is that President Obama will be speaking at 12.15pm – given his habitual lateness, let's assume 12.45pm.

Mitt Romney is holding a press conference in DC at time unknown – but probably he'll wait for Obama to speak.

Meanwhile, the anti-healthcare reform attack ads are running on cable news.

Today's decision just goes to show how wrong it is possible to be about the supreme court. Everyone, and I mean, everyone, said that Anthony Kennedy was going to be the swing vote. Well, he voted against it en bloc. Meanwhile, George Bush appointee John Roberts saved Obama's healthcare reforms.

President Obama is going to make a public statement within the next 45 minutes, we're told.

The reaction inside the White House is said to be "elation" according to a CNN person standing outside the White House.

The Guardian's Washington bureau chief Ewen MacAskill offers his instant reaction to the supreme court decision upholding the bulk of Barack Obama's signature healthcare reforms:

This is a big win for Barack Obama. The legislation that he staked the first term of his presidency on emerges from the supreme court largely intact. If he wins the election in November, then his health care reform, due to kick in in 2014, will go ahead as planned. Polls show that opinion has remained evenly divided since its passage in 2010. But the parts of the legislation that have already been enacted are proving popular and once the rest of it is in place, the reform may become accepted and even popular in the way Medicare and Medicaid have become. If the supreme court had gone the other way, it would have been a disaster for Obama. He would have been vulnerable to Mitt Romney's charge this week that he had wasted the first three and a half years of his presidency. Health care will be an issue in the election campaign but it will have the same impact as it would have had the supreme court gone the other way. Romney will continue to campaign against health care reform and pledge to reverse it if he becomes president. But it is harder for him now. It would have been so much easier to mount attacks amid the wreckage of a negative supreme court decision. The Republicans had been looking to turn Thursday into a bleak day for the Obama administration, starting with the supreme court ruling in the morning and the contempt vote against Eric Holder in the House in the afternoon. The House will vote for contempt but its impact will be lost amid the euphoria in the White House over the supreme court ruling.

And the reaction is flooding in. Here's a statement from Speaker of the House John Boehner:

Today's ruling underscores the urgency of repealing this harmful law in its entirety. What Americans want is a common-sense, step-by-step approach to health care reform that will protect Americans' access to the care they need, from the doctor they choose, at a lower cost. Republicans stand ready to work with a president who will listen to the people and will not repeat the mistakes that gave our country Obamacare.

Not a gracious defeat, then.

Here's an explanation on the Medicaid expansion inside the Affordable Care Act, which is estimated to have provided health insurance to 16 million currently uninsured lower-income people.

Under the ACA, eligibility for Medicaid was to be widened:

The new law expands Medicaid to a national floor of 133% of poverty ($14,404 for an individual or about $29,326 for a family of four in 2009) to help reduce state-by-state variation in eligibility for Medicaid and also include non-Medicare eligible adults under age 65 without dependent children who are currently not eligible for the program. Children currently covered by CHIP between 100% and 133% of poverty would be transitioned to Medicaid coverage. These changes help to provide the base of seamless and affordable coverage nationwide through Medicaid for those with incomes up to 133% of poverty and then subsidies for coverage for individuals with incomes between 133% and 400% of poverty through state-based Health Benefit Exchanges. Individuals eligible for Medicaid would not be eligible for subsidies in the state exchange. For most Medicaid enrollees, income would be based on modified adjusted gross income without an assets test or resource test.

Under the supreme court decision, it appears, individual states can refuse to accept the Medicaid expansion.

The court's ruling on the Medicaid expansion makes today's decision somewhat reminiscent of the Arizona immigration ruling – the court has left a depth charge inside its decision.

The Medicaid expansion would have offered health insurance coverage to 16 million people. Now states apparently can make up their own minds whether or not to accept the expansion – and that means if Florida, Texas and other big states knock it back, then there will be millions of Americans who will miss out on the benefits of the healthcare reforms.

On the Medicaid expansion: the court has ruled that the government can only offer a carrot in terms of higher funding, but not the stick of taking away all of a state's Medicaid funding.

States have complained that the expansion costs them money, despite the extra funding they'll receive. Now they can turn down the expansion, which offers the expansion of coverage to mainly low income people without health insurance.

We'll need to see some analysis of the consequences of this decision, and which states may decide to snub their noses at the Medicaid expansion.

The history of the supreme court is that presidents make appointments and are often disappointed by their subsequent career. Has John Roberts joined the likes of Warren Burger and David Souter?

There's a big silver lining here for Obamacare opponents. Here's the majority opinion on the Medicaid expansion, as written by Roberts:

Nothing in our opinion precludes Congress from offering funds under the ACA to expand the availability of health care, and requiring that states accepting such funds comply with the conditions on their use. What Congress is not free to do is to penalize States that choose not to participate in that new program by taking away their existing Medicaid funding.

That means that states that refuse to accept the federal government's expansion of Medicaid can't be penalised by the government – the status quo remains.

That's actually a tricky decision, and it can be read as a defeat for the Obama administration. It puts the ball back in the court of the states that – for whatever reason – want to reject the Medicaid expansion, which is a key part of the reform's attempt to expand healthcare coverage.

This blows a hole inside the Affordable Care Act. Hold off popping those champagne corks.

In the detail: the supreme court appears to have also redefined the commerce clause and tightened its use. The clause's power has been trimmed by the court in recent decision, but this is another attempt to box it in further.

Here's the key quote to maintain the individual mandate as constitutional, from Roberts's opinion:

Our precedent demonstrates that Congress had the power to impose the exaction in Section 5000A under the taxing power, and that Section 5000A need not be read to do more than impose a tax. This is sufficient to sustain it.

That's clear, right? Me neither.

Once again, this is a long, complex and multi-layered decision by the supreme court, and the voting may have differed on different points – so take nothing for granted.

But it appears that John Roberts joined the liberal wing in upholding the healthcare law and individual mandate. This is significant in itself and news that will sink the US conservative movement into deep gloom.

Wow: it appears that the so-called swing vote on the court, Anthony Kennedy, actually joined Scalia, Alito and Thomas in voting against the law – and that Chief Justice Roberts voted to uphold.

Now there's a turn-up for the books.

Opinion seems to be that the Affordable Care Act has been upheld – but there's a lot of detail in there, so more as it comes.

So the individual mandate appears to have survived as constitutional, not under the commerce clause but as a tax, and that Chief Justice Roberts has joined the "liberal" wing of the court on the issue.

More important news: the Medicaid expansion is limited but not invalidated by the decision. The devil is in the details but if that's broadly the case that's another big win for the administration.

No news on votes or dissents yet.

As suggested earlier – this is a complex decision, so it's worth waiting to see how the whole decision reads.

It appears that the individual mandate may survive as a tax. More as we get it.

Hold on – while Roberts appears to have invalidated the individual mandate under the commerce clause, ScotusBlog is saying the mandate has survived as a tax. Let's wait and see how this plays out.

Here we go: Chief Justice John Roberts is reading the decision on healthcare law now – so that means he wrote the decision – and the mandate fails under the commerce clause.

More as we get it.

The court has published its first decision, but it's about something else involving the first amendment. Oh it's the Stolen Valor act – which bans people falsely claiming they have won military honours (surprisingly common in the US, for some reason).

Anyway, it's unconstitutional but Congress can redraft it. Apparently it's not illegal to lie. Thomas, Scalia and Alito all dissent.

While we are waiting, here's a nice photo of the supreme court justices.

They all have a great health insurance deal.

Five minutes to go. There's a tiny but non-negligible chance that the court will punt on the whole issue, thanks to the Anti-Injunction Act that holds that taxes cannot be challenged in court until they are first levied. Which hasn't happened yet. But it's not likely.

But if the court did, that would be really bad for everyone's health.

Fifteen minutes to go – and when the healthcare rulings come, it's likely to be a complex one with many layers and possibly multiple dissents – as the Arizona immigration ruling on Monday showed – so beware of over-caffinated responses declaring victory for one side or the other.

The fate of the individual mandate is only one aspect, although it's obviously the biggest one. Another, perhaps more far reaching in constitutional terms, is how the court redefines the commerce clause that the government is using to justify the mandate.

And then there's the so-called Medicare expansion issue, offering healthcare coverage to an additional 16 million people but from which some states are asking the court to allow them to opt out. That alone could be even more significant than a decision on the individual mandate.

In all the political excitement over today's ruling, let's not forget what's at stake: the nearly 50 million Americans without health insurance.

In the event of the supreme court upholding the Affordable Care Act, how will the Republicans react? After the apoplexy has faded, here's what Speaker of the House John Boehner said yesterday:

If the court does not strike down the entire law, the House will move to repeal what's left of it.

Here's a brief history of Barack Obama's conflicts with the supreme court, starting with Chief Justice John Roberts bungling the oath of office at Obama's inauguration, Samuel Alito mouthing criticism at Obama during the 2010 state of the union address, and so on.

Here's one supreme court prediction that is worth remembering, by two political scientists back in November last year, who tried to model the outcome:

As always, predictions are hard, especially about the future (see Berra v Bohr) and especially when it isn't clear which precedents apply or which legal doctrines are likely to dominate. Thus, any specific prediction must go beyond the model. That said, here is ours: 6-3 or 7-2 to uphold the law. Respect for precedent pushes Kennedy to support the law and Roberts comes along for the ride in order to keep the opinion out of Kennedy's hands (and possibly writing an opinion that cabins the Commerce Clause more than it is now). Alito probably goes with Roberts, but seems more up for grabs. If we are wrong, expect the justices to either downplay precedent and emphasize other legal values (such as federalism) or play up the few precedents that protect state rights.

We'll all find out in about 30 minutes.

The New York Times's Nate Silver says that no one really knows what the decision is gong to be today:

[S]tudies have found that predictions made by "expert" commentators on the Supreme Court do barely any better than a coin flip and are beaten by the statistical methods (a finding that follows the poor overall track record of experts in making predictions under many other circumstances). These experts are irrationally confident about their ability to read the tea leaves, and their predictions suffer for it.

That makes me feel better that I have absolutely no clue what the result will be.

Of course you can follow all the healthcare decision news here but if you are a hard-core junkie then you can mainline the supreme court decision on ScotusBlog.

Never one to miss an opportunity, the Obama for America campaign manager Jim Messina emails supporters:

Friend – We don't know what will happen this morning. But no matter what, today is an important day to have Barack Obama's back. If you're with him, donate now – before this week's critical fundraising deadline.

But don't worry, the Romney campaign will be spitting out fundraising emails soon enough.

Right: an hour to go until the supreme court hands down its decision. It's a great day to bury bad news, as someone once said.

Bad news such as...

Losses on JP Morgan Chase's bungled trade could total as much as $9 billion, far exceeding earlier public estimates, according to people who have been briefed on the situation. When Jamie Dimon, the bank's chief executive, announced in May that the bank had lost $2 billion in a bet on credit derivatives, he estimated that losses could double within the next few quarters. But the red ink has been mounting in recent weeks, as the bank has been unwinding its positions, according to interviews with current and former traders and executives at the bank who asked not to be named because of investigations into the bank.

Well, well, fancy that.

So how is the White House preparing for the range of outcomes this morning? Three different speeches for President Obama, according to the Wall Street Journal:

The president has three separate speeches prepared in anticipation of the ruling on his signature legislative achievement, a person familiar with them said. One of the speeches addresses a complete overturn of the law, while another is crafted as if the court strikes down the law's individual mandate but upholds other provisions. The third speech, for if the court upholds the entire law, is more celebratory, according to this person. No matter the ruling, the White House is expected to continue highlighting provisions of the legislation that are more popular than the overall law, such as the requirements that insurance companies cover people with pre-existing conditions or allow parents to keep their children on their plans until they are 26 years old. It's unclear when Mr Obama will comment on the decision. It's not on his public schedule. He is scheduled to be in the Oval Office receiving the daily presidential intelligence briefing at 10am, around when the decision is expected to be announced.

The US supreme court will today announce its decision on the Affordable Care Act, 828 days after the Obama administration's package of healthcare reforms passed into law.

In the court's most controversial decision since Bush versus Gore decided the 2000 presidential election, the focus is foremost on the constitutionality of the individual mandate, the provision requiring Americans to have health insurance and the main bone of contention of those who oppose the law as an unwarranted extension of the federal government's powers.

The court's decision will be handed down shortly after 10am in Washington DC – and with no leaks or hints surrounding the decision, even experienced court watchers confess uncertainty over how the nine supreme court justices will decide the challenge to the law brought by several states.

We will be live blogging the ruling, its implications and the seismic reactions that are sure to follow, no matter what the result – with the effects rippling beyond today's announcement to the presidential election to be held on 6 November.

Republican challenger Mitt Romney has pledged to abolish the healthcare reforms if the supreme court fails to do so, while the White House is said to be ready with a back-up plan, involving a series of executive orders, if the healthcare law is overturned.

Background briefing:

• A beginner's guide to the healthcare ruling, by Lyle Denniston of ScotusBlog, the foremost source of supreme court intelligence

• The Associated Press has an excellent Q&A about the possible outcomes from today's decision and their implications

• The New York Times has an interactive graphic to explain the ruling and its consequences

• Politifact.com's top five falsehoods about the healthcare law – including Sarah Palin's "death panel" claim that earned her a "pants on fire" rating

• Follow audio excerpts and the supreme court's transcript from important points in March's hearing

• Read the Guardian's full coverage of the US healthcare debate