Since becoming chief justice 10 years ago,
In the phrase he used at his confirmation hearings, each justice is "like an umpire" at a baseball game — not favoring one team over the other.
On Thursday, Roberts showed again his willingness to brush aside partisan politics and forge a middle ground on some of nation's most divisive issues, writing a 6-3 decision that upheld the broad reach of President
It was the second time in three years that Roberts had led the
"We might as well call the law … RobertsCare," said Ilya Shapiro, a lawyer at the Cato Institute, a libertarian think tank in Washington.
When Roberts spoke of being an umpire, "a lot of people on the left sneered," said
Roberts cringes at the regular references to the "conservative bloc" or the "liberal wing" of the court. Last year, he was pleased when the justices were able to agree unanimously in a much higher percentage of their cases.
Thursday's decision sent a particularly loud message about a nonpartisan court because the chief justice gave a generous reading to a liberal law passed by a Democratic-controlled Congress.
But the decision is not a sign that Roberts has become a liberal or shifted strongly to the left, as some allege.
On the same day, Roberts joined three conservatives in dissent when the majority held that the Fair Housing Act forbids practices that have a "discriminatory effect" on racial minorities even if there is no intentional discrimination. In 2013, he voted with conservatives to strike down part of the Voting Rights Act.
His decisions on easing campaign finance rules, including Citizens United, which gave corporations and unions the ability to make unlimited contributions to political causes, firmly established Roberts' record as a conservative.
But on most issues, the chief justice has shown himself to be most comfortable in the moderate middle and unwilling to push the law too far to the right or too quickly.
In April, he joined with the court's four liberal justices to uphold a Florida law that prohibited elected judges from personally soliciting campaign contributions. Roberts supports the 1st Amendment right to spend freely on campaigns, but judges are not politicians, he said.
In other alliances with liberals, he helped forge a 6-3 majority to rule that a police officer may not detain a car stopped for a traffic violation so a drug-sniffing dog may be brought to the scene. He also joined a 5-4 opinion by Justice
Further evidence on how Roberts sees his role could come as early as Friday in the court's decision on gay marriage. It's widely expected that a majority of justices will declare the right of gays and lesbians to marry nationwide, but given Roberts' growing independent streak, combined with the impact that case will undoubtedly have on his legacy, some are wondering whether the chief justice will find a way to side with liberals in what would be a landmark decision.
Roberts' reasoning in the healthcare case showed several of his characteristic traits — a desire for moderation as well as a concern over the real-world impact of the court's decisions, particularly on business.
Had the justices ruled for the conservative activists who sued the administration, more than 6.4 million people could have lost their health coverage. That in turn could "well push a state's individual insurance market into a death spiral," Roberts said.
It would be "implausible," he said, to think the Congress that passed the healthcare law intended to limit its tax subsidies to the 13 states that established an exchange, or marketplace, of their own.
He rejected the claim brought by conservative activists who pointed to one part of the law that said subsidies were limited to insurance policies bought on an exchange "established by the state." This hyper-technical reading of one phrase did not make sense and was contradicted by other parts of the law, he said.
"Congress passed the Affordable Care Act to improve health insurance markets, not to destroy them," he wrote.
Duke law professor Neil Siegel called the majority opinion "a masterpiece of legal craft, good sense and fidelity to the law at a time when political polarization threatens to spill over into the judiciary."
But the three conservative dissenters accused the majority of "interpretive jiggery-pokery" and "somersaults of statutory interpretation" to fix a political, not legal, problem.
"This court's two decisions on the [healthcare] act will surely be remembered through the years," wrote Justice
In most cases, however, Roberts is still somewhat more likely to vote with the court's conservatives than its liberals. University of Chicago Law professor David Strauss said the final word about the Roberts court wouldn't come until it weighs in on broad major issues such as abortion and race.
"But the chief justice has made it clear that he meant what he said in his confirmation hearings: The big decisions should be made by the people who won an election, whether the court agrees with them or not, as long the justices don't have to distort the law to do that," Strauss said.