"We decide who comes into this country and the circumstances in which they come" is one of the most potent lines ever spoken by an Australian political leader.

Delivered by John Howard in 2001, it transformed Australia, and 18 years on, our political leaders are still dealing with its message and its legacy.

The so-called Tampa affair is seared in the memory of ALP hardheads who have a long memory and cannot forget the electoral consequences of that crisis and the subsequent decisions they made in government after 2007, which effectively restarted the people-smuggling trade and put them in a world of political and policy woe.

On this issue Labor has always been on the backfoot — it knows it and under Bill Shorten it has been shrewd in carefully avoiding being trapped talking about it.

There's no greater example of this avoidance than the very low profile of Labor immigration spokesman Shayne Neumann.

His job has been to avoid getting himself in the news. If the country isn't talking about boats, Labor has felt that it is on safer ground.

The so-called Tampa affair is seared in the memory of ALP hardheads. ( AAP )

Labor MPs are prepared to fight

The idea that Labor cannot possibly win the argument on border protection policy has become political orthodoxy.

It is this crucial context which makes what happened on Wednesday morning in the Senate extraordinary.

Legislation that will give doctors more power to decide whether asylum seekers should come to Australia for medical treatment has been passed into law by the Senate.

It's a done deal. It is the law of the land.

The Morrison Government must now implement a policy it argues makes our borders vulnerable.

Sorry, this video has expired PM announces immigration measures in response to refugee bill's passage

The Prime Minister argues that he will keep the borders strong, but also argues that the boats could be on their way.

Mr Morrison put it this way: "So if they don't come, it will be because of the work and the decisions we are now taking and the actions we are putting in place.

"If they do come, you can thank the Labor Party and Bill Shorten because he is the one who has led this process."

Labor knows it has taken a hefty political gamble by supporting the medical evacuation bill. It has not walked into this decision naively. Senior Labor figures have war gamed its consequences.

Labor is acutely aware of the blitzkrieg it is about to face on boats and Labor MPs tell me they are prepared and ready to fight.

'People smugglers don't deal with the Canberra bubble'

Labor has made the political calculation that something has changed in Australia and that it is in the unique position to win this debate.

It is a heroic level of confidence given the significant history here.

Labor has been preparing for the Government to turn the volume up to 11 and now we know how high that volume is likely to get.

The Prime Minister claims the new law, which will let sick refugees come to Australia, will restart the people-smuggling trade.

He argues any protections in the medevac bill will not stop people smugglers encouraging refugees as the laws have been fundamentally "weakened".

He described as "nuance" a critical part of the bill that means the medical assessments would only apply to the current cohort of offshore asylum seekers.

That means that if a boat were to arrive tomorrow, no-one on that boat would have access to these new laws.

"People smugglers don't deal with the nuance of the Canberra bubble," the PM said.

"They deal with the psychology of messagings of whether things are stronger or whether things are weaker.

"It might be all fine and nice to talk about these nuances here in this courtyard, but when you're in a village in Indonesia and someone is selling you a product, there's no protections or truth in advertising laws for people smugglers.

"They just sell the message."

The Government's wicked problem

He may have lost the historic vote in Parliament but after meeting with his national security committee, Mr Morrison has now revealed that Australia will reopen its detention facilities on Christmas Island.

"We have approved putting in place the reopening of the Christmas Island detention facilities, both to deal with the prospect of arrivals as well as dealing with the prospect of transfers," he said.

The imagery is powerful.

The Christmas Island detention centre stands as a symbol of a time when scores of boats arrived, crashing into rocks with desperate people dying, sending shockwaves across the nation.

What message does the reopening of Christmas Island detention centre send to people smugglers? ( AAP: Mick Tsikas )

It was only late last year that the Morrison Government quietly closed the Christmas Island detention centre. It signified the end of an era.

Now the Government has sent an alarming message to voters that it needs to be recommissioned — and with that image it hopes to remind Australians of its unsettling history.

Immigration Minister David Coleman argues that the Government has now been forced to reopen Christmas Island at a cost on hundreds of millions of dollars to the taxpayers.

So what's the message to people smugglers? The Prime Minister says he is the minister who stopped the boats and he will continue in that mission, despite being hamstrung by new laws the Government had no control over.

But the question remains, what message does the reopening of the Christmas Island detention centre send to people smugglers?

The Government has a wicked problem here. It argues only it can stop the boats, but the Prime Minister is now openly saying that Australia's laws are weak and open to exploitation.

My colleague in Indonesia, David Lipson, says few in Indonesia noticed or cared that the Government lost the medevac bill, but "the Prime Minister's announcement that he's reopening Christmas Island for business is making a splash".

Politicians have never been very good at nuance, and they expect that voters are not terribly receptive to it either.

Labor now embarks on a deeply difficult project. It wants voters to believe it is tough on borders, but compassionate when asylum seekers are desperately sick.

If it can communicate that message effectively and with conviction, it will rewrite an 18-year-old political script.