We are reporting todayon the Supreme Court's 6-3 decision to uphold the nationwide subsidies called for in the Affordable Care Act. The court's majority opinion was written by Chief Justice John Roberts, who was joined by the court's liberal justices, as well as Justice Anthony Kennedy.

The Majority's Rationale

At issue is Section 36B of the Affordable Care Act, which refers to "an exchange established by the state." As NPR's Nina Totenberg reported in April: "The government [contended] that those words refer to any exchange, whether it is set up by the state itself or an exchange run for the state by the federal government in accordance with individual state insurance laws and regulations. The challengers [said] the statute means what it says and no more."

Roberts, in his opinion noted, that the phrase is open to interpretation.

Who Interprets?

Courts typically defer to a federal agency's interpretation – in this case the IRS — as long as, in the words of Julie Rovner of Kaiser Health News, "that interpretation isn't unreasonable." This is referred to as the "Chevron deference," a legal principle that takes its name from a 1984 Supreme Court case. In today's opinion, Roberts essentially said this isn't "a case for the IRS." In other words, it's up to the court.

Upholding The Law

Roberts also noted why the court "must interpret the law" so health insurance markets are improved. Here's what he wrote:

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