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Barack Obama with John Roberts
(McClatchy-Tribune)

(The Root) -- Chief Justice John Roberts has held the role of "swing justice" in the past, casting the deciding vote in close Supreme Court cases. But his decision to side with the center-left justices in Thursday's Affordable Care Act ruling, upholding the individual mandate, still came as a surprise.

While the vote to reaffirm President Obama's signature piece of legislation is being hailed as a boon to the president's re-election campaign, the substance of Roberts' opinion stops well short of actually championing the policy. From the opinion:

Members of this Court are vested with the authority to interpret the law; we possess neither the expertise nor the prerogative to make policy judgments. Those decisions are entrusted to our Nation's elected leaders, who can be thrown out of office if the people disagree with them. It is not our job to protect the people from the consequences of their political choices.

With his careful "this is not about politics" ruling, Roberts avoids accusations of judicial activism or overreach by not completely striking down the health care reform law. By shifting the individual mandate argument away from the Commerce Clause, reframing the provision as a tax, he also managed to still uphold conservative legal ideology.

"He got away from the problem that the conservatives would have had if he'd argued that it's OK to force people to buy things under the Commerce Clause," Abigail Moncrieff, professor of law at Boston University School of Law, told The Root. "But it also avoids the institutional problem of having the court invalidate such a big political decision."

Moncrieff added that the Supreme Court, historically, has tried to be modest in second-guessing legislative and political decisions. "Throughout the opinion, Roberts is very interested in this idea of judicial restraint and trying to make sure that the court doesn't do too much," she said.

In his reaction to the Supreme Court decision, Mitt Romney emphasized that the ruling was far from a ringing endorsement of the Affordable Care Act. "What the court did today was say that Obamacare does not violate the Constitution. What they did not do was say that Obamacare is good law or that it's good policy," Romney said on Thursday. "This is a time of choice for the American people. Our mission is clear: If we want to get rid of Obamacare, we're going to have to replace President Obama."

Romney's rallying cry against the law may very well re-energize the Republican base, since a Romney administration would have the power to undercut the law's implementation with or without control of Congress.

The way that the Supreme Court ruled could also make things more difficult for Obama. "Now, based on Justice Roberts' opinion, in his re-election campaign President Obama has to say that he increased taxes," said Moncrieff. "And not only that, increased taxes on the middle class. Because among the people who are most likely to not have health insurance are lower-middle-class individuals. So on this issue, Romney will have a bit of ammunition."

Nonetheless, President Obama will no doubt use the Supreme Court decision to make a campaign argument for his re-election. In his own remarks on Thursday, however, he claimed to be uninterested in how it will play for him politically. "That discussion completely misses the point," Obama said. "Whatever the politics, today's decision was a victory for people all over this country whose lives will be more secure because of this law and the Supreme Court's decision to uphold it."

Cynthia Gordy is The Root's senior political correspondent.

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