When the U.S. Supreme Court made a Medicaid expansion optional under the Affordable Care Act, the decision lowered the estimated cost of the law. Chip Somodevilla/Getty Images hide caption

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The U.S. Supreme Court, 70 years after rejecting Roscoe Filburn's bid to limit the federal government's power to regulate commerce. Chip Somodevilla/Getty Images hide caption

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The U.S. Supreme Court justices (first row, from left) Clarence Thomas, Antonin Scalia, Chief Justice John Roberts, Anthony Kennedy, Ruth Bader Ginsburg, (back row) Sonia Sotomayor, Stephen Breyer, Samuel Alito and Elena Kagan. Supreme Court hide caption

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Joy Reynolds of San Diego, Calif., looks over Friday's front pages on display at the Newseum in Washington, the day after the Supreme Court ruling on President Barack Obama's health care law. David Goldman/AP hide caption

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Chief Justice John Roberts, shown in 2010, is still "finding his role as chief justice," says one law professor. Paul J. Richards/AFP/Getty Images hide caption

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Protesters and supporters of President Obama's health care law await the Supreme Court's ruling Thursday. The court ruled to uphold the law. The focus now shifts to the states, which are responsible for the lion's share of getting people without insurance covered. Kevin Dietsch/UPI /Landov hide caption

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Kailash Sundaran (left), Devyn Greenberg and Devontae Freeland celebrate the Supreme Court's ruling upholding the Affordable Health Care Act outside the court Thursday. Alex Wong/Getty Images hide caption

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