Chief Justice John Roberts wrote the court's majority opinion and was joined by Justices Anthony Kennedy, Ruth Bader Ginsburg, Stephen Breyer, Sonia Sotomayor and Elena Kagan.

Should the Court have struck down the subsidies, it would have had disastrous effects for the health care market and the health reform law. An estimated 6.4 million Americans receive the subsidies in the 34 states that don't have their own exchanges. Reports had suggested millions would lose coverage and millions more would suffer from exploding premiums had the government lost in King v. Burwell.

The Supreme Court agreed.

“The combination of no tax credits and an ineffective coverage requirement could well push a State's individual insurance market into a death spiral. It is implausible that Congress meant the Act to operate in this manner,” Roberts wrote.

King v. Burwell ultimately hinged on just four words—“established by the state”—as it called into question the legality of federal exchanges. While PPACA challengers said that phrase limits the tax credits to the 16 states that have set up their own exchanges, the Obama administration repeatedly defended an IRS rule that interpreted the law as allowing subsidies nationwide.

The case represented the biggest legal threat to PPACA since the law was challenged in the Supreme Court three years ago. Then, the court upheld the law's centerpiece, the individual mandate, as a tax by a 5-4 vote, but left Medicaid expansion up to the states.

The Obama administration also did not have a backup plan had the subsidies been gutted.

Ultimately, this was the decision most had hoped for: Poll after poll found that the public backed the subsidies and wanted the court to uphold all the law's subsidies, regardless of whether they supported PPACA in general.

Many in the industry praised the decision.

The National Business Group on Health said the ruling was “welcome news” to large employers in “affected states which have relied on exchanges for health insurance for early retirees, part-time employees, and other employees.”

“Millions of Americans, including employees, retirees and their families can now rest assured that they will continue to have access to federal subsidies that help keep their health insurance coverage affordable,” said Brian Marcotte, NBGH President and CEO. “It also reassures employers in affected states which have relied on exchanges for early retirees, part-time employees and other employees, that there will be no disruption in coverage.”

Despite the administration's victory, analysts do not see this being the end of controversy for PPACA.

“Affordable Care Act implementation returns to normal following [the] ruling but debate over the law is likely far from over,” said Elizabeth Carpenter, director at consulting firm Avalere Health. “Congress may still pursue strategies to alter the Affordable Care Act, and the debate over reform is likely to reignite as part of the 2016 presidential race.

“Congress is still likely to consider repeal of the medical device tax and the Independent Payment Advisory Board, as well as changes to the employer mandate and the Cadillac tax.”