Maurine Stuart credits the Affordable Care Act (ACA) for saving her family. In 2014, Stuart was diagnosed with HELLP syndrome, a rare disease that causes heart, liver and lymphatic problems. As a result, she was unable to continue working full time—which meant losing her employer-sponsored health insurance. But thankfully, she says, that same year, her home state of West Virginia opted in to the 2010 Affordable Care Act's Medicaid -coverage expansion, and she qualified.

Over the next few years, as bad news kept rolling in, ACA protections continued to keep Stuart's family afloat. When Stuart was diagnosed with breast cancer, when her sister was diagnosed with a brain tumor, and when her daughter Peyton began having seizures, the ACA consistently offered avenues of affordable care. Stuart and her sister received coverage under the Medicaid expansion, while Peyton got it through the Children's Health Insurance Program, which had been strengthened under the ACA.

Stuart says the ACA not only gave her and her family access to the treatments they needed, it also changed their mentality about when to seek out professional care in the first place. When she and her siblings were growing up in California in the 1980s and '90s, they couldn't afford health care, Stuart says. "The criteria for going to the doctor was, 'Are you bleeding? Have you lost a limb?'" Her father and brother never shook that idea, Stuart says. Despite the passage of the ACA, they never got insurance. They thought it would be too expensive. So in recent years, when both of them began having severe health issues, neither regularly went to the doctor. By 2016, both men were dead: her father from prostate cancer and her brother, at 19, from a massive pulmonary embolism.

"My dad and my brother died; my sister, my daughter, me, we all lived," Stuart says. "The common denominator," she says, was health insurance.

It's been 10 years since President Barack Obama signed the Affordable Care Act into law—and proudly embraced its once pejorative nickname, Obamacare. But the law's legacy remains at least as layered and complicated as Stuart's family medical history. Thanks to the ACA, 20 million people in the U.S. gained health coverage, and early studies show the law improved the health of Americans across a range of measures. It also helped narrow racial, gender and ethnic gaps in coverage. Between 2013 and 2018, the uninsured rate dropped 10% for black adults and by more than a third for Hispanic adults. Other groups, including women and young people, saw significant gains in coverage as well.

But the law is also deeply flawed. Despite its framers' high hopes, plenty of health outcomes have not improved, marketplace insurance plans have remained too expensive, and while national health care spending has been lower than predicted, the ACA's record on containing costs is a mixed bag.

In many ways, the ACA today serves as a kind of sociopolitical Rorschach test in the U.S. To many mainstream Democrats, the law is an imperfect victory: in 2018, they won the majority in the House of Representatives in part by trumpeting a platform of protecting—and improving—the ACA. Progressives, meanwhile, see the law as not going nearly far enough.

To many Republicans, the law is a bête noire. Congressional Republicans have voted at least 70 times to dismantle, defund or change the ACA, and conservatives have brought three major challenges to the law to the Supreme Court. Fourteen states, most with Republican governors, still refuse to opt in to the law's Medicaid expansion, and the Trump Administration has successfully chipped away at a handful of the law's crucial rules. But in 2017, when Republicans got their chance to kill the ACA outright, they balked. Despite having majorities in the House and Senate, they couldn't agree on a replacement—and the late Senator John McCain prevented an outright repeal, which would have left a great deal of Americans without access to insurance at all. Today, 55% of Americans support the law, an all-time high, according to the Kaiser Family Foundation's latest poll.

One of the ACA's most popular provisions ensures that people with pre-existing conditions cannot be denied coverage or charged higher premiums. Before its passage, insurers could charge excess prices for—or outright deny—coverage to all kinds of people, including pregnant women and cancer survivors. The ACA also eliminated annual and lifetime limits on coverage, a change that protects people who have had prior health emergencies.

Perhaps unsurprisingly, researchers have found that having good insurance directly correlates with better access to care--which in turn often translates to better health. Increases in coverage due to the ACA led to an uptick in early cancer diagnoses; improved rates of treatment for diabetes, high blood pressure and kidney disease; and better self-reported health, studies find. There have been other highlights too: some studies show Medicaid expansion helped people get evidence-based treatment for opioid addiction and to quit smoking. More broadly, researchers have found that the ACA reduced medical debt nationwide, lowering bankruptcy and poverty rates.

These improvements have helped reduce annual mortality rates for infants and people with cardiovascular disease, especially in states that opted in to expanded Medicaid. One study found that if all 50 states had expanded Medicaid, as the ACA's framers intended, it likely would have saved 15,600 lives from 2014 to 2017.

A foundational idea of the ACA was that it was supposed to preserve free-market competition by creating state-based marketplaces where people could buy private health insurance. Only it didn't turn out that way. Once the ACA went into effect, sick people—who require the most costly care—flooded the marketplaces, and many healthy people did not join at all. The results were grim: the cost of premiums rose, and many insurers, assessing the marketplaces as unprofitable, bailed. That meant that customers in many regions were left in the lurch: they could choose from only a handful of often very pricey plans.

And then it got worse. Under the ACA, those with incomes up to 400% of the federal poverty level received subsidies to help them afford expensive insurance plans. But many middle-class Americans made too much to qualify for that help yet far too little to afford to pay on their own. The high deductibles on marketplace and employer-sponsored plans have left more people underinsured than 10 years ago.

The Trump Administration has relentlessly pushed to dismantle the ACA. It has managed to get the individual mandate ruled unconstitutional; allowed plans that skirt ACA coverage requirements; slashed funds that helped people sign up for insurance; and imposed new regulations on Medicaid, such as new premiums and work requirements. As a result of these efforts, the ACA is weaker now than it was a decade ago, and the number of Americans with health insurance has declined.

But the law's impact remains strong, in part because it transformed the way Americans think about the role of government in health care. It stretched what they thought was possible. In the decade since former Vice President Joe Biden called the ACA a "big f-cking deal" on the day it was signed into law, Pew research shows that the majority of Americans have come to believe that it is the federal government's responsibility--through the ACA or its eventual replacement--to ensure health care to all Americans.

Stuart in West Virginia says she remains grateful to the ACA for providing her family coverage over the years. Her breast-cancer prognosis now looks good, and her daughter Peyton is tapering off her antiseizure medication. But with ongoing legal challenges to the ACA and President Trump in the White House, she worries that one day it will be repealed. "I wake up every day afraid," she says.

With reporting by Alice Park