US Supreme Court

Washington (CNN) Obamacare has survived — again.

In a major win for the Obama administration, the Supreme Court held in a 6-3 decision that the Affordable Care Act authorized federal tax credits for eligible Americans living not only in states with their own exchanges but also in the 34 states with federal exchanges.

Chief Justice John Roberts wrote for himself, Justice Anthony Kennedy and the four liberal justices. Justice Antonin Scalia wrote the dissent, joined by Clarence Thomas and Samuel Alito.

The ruling staved off a major political showdown and what would have been a mad scramble in some states to set up their own healthcare exchanges to keep millions from losing healthcare coverage.

Challengers to the law argued that the federal government should not be allowed to continue doling out subsidies to individuals living in states without their own healthcare exchanges and a ruling in their favor would have cut off subsidies to 6.4 million Americans, absent a congressional fix or state action.

The ruling is a huge victory for President Barack Obama who nearly saw those four words in the Affordable Care Act throw his signature achievement into chaos.

The income-based subsidies are crucial to the law’s success, helping to make health insurance more affordable and ultimately reducing the number of uninsured Americans, and shutting off the subsidy spigot to individuals in the 34 states that rely on exchanges run by the federal government would have upended the law.

Congress would have had to amend the Affordable Care Act to fix the “established by the state” language — a politically treacherous and likely untenable action in a Republican Congress — or governors in the 34 states without their own exchanges, most of them Republicans, would have had to establish their own exchanges — another tough ask.

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