This artist's rendering shows Chief Justice John Roberts (center) speaking at the Supreme Court on Thursday. From left are Justices Sonia Sotomayor, Stephen Breyer, Clarence Thomas, Antonin Scalia, Roberts, Anthony Kennedy, Ruth Bader Ginsburg, Samuel Alito and Elena Kagan. The court voted 5-4 to uphold President Obama's health care law. Dana Verkouteren/AP hide caption

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Former pitcher Roger Clemens, center, and his attorneys Rusty Hardin, right, and Michael Attanasio arrive on the courthouse steps after Clemens was found not guilty on all charges in his perjury trial at U.S. District Court in Washington, D.C., on Monday. Saul Loeb/AFP/Getty Images hide caption

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Former pitcher Roger Clemens leaves a federal court in Washington, D.C., on Tuesday. His fate is in the hands of a jury that will decide whether the former pitcher lied about his use of performance-enhancing drugs. Manuel Balce Ceneta/AP hide caption

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For more than 200 years, the Supreme Court has interpreted the meaning of the Commerce Clause of the Constitution. Its latest test is the case challenging the Obama health care law. Mark Wilson/Getty Images hide caption

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Mary Bonauto, the lawyer for the couples who challenged the Defense of Marriage Act, addresses the media after a hearing at the U.S. Court of Appeals on April 4 in Boston. John Tlumacki/AP hide caption

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Brian McNamee, Roger Clemens' one-time trainer, leaves federal court in Washington, D.C., on Wednesday. Jacquelyn Martin/AP hide caption

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Totenberg teaches student Letitia Hom in his classroom at Boston University. Totenberg made his debut as a soloist with the Warsaw Philharmonic at age 11. David L. Ryan/The Boston Globe via Getty Images hide caption

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Andy Pettitte leaves the courthouse after testifying Wednesday in the perjury and obstruction trial of former teammate Roger Clemens in Washington, D.C. Win McNamee/Getty Images hide caption

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Andy Pettitte leaves the federal court in Washington, D.C., Tuesday. Pettitte took the stand in the retrial of Roger Clemens on charges that Clemens lied when he told Congress in 2008 that he had never used steroids or human growth hormone. Manuel Balce Ceneta/AP hide caption

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Arizona Gov. Jan Brewer speaks to reporters outside the Supreme Court on Wednesday, after oral arguments on Arizona's immigration law. At left, in brown and wearing sunglasses, is NPR's Nina Totenberg. Charles Dharapak/AP hide caption

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