Use of synthetic "bath salts," compounds sold legally but used as a controlled substance, has been on the rise since 2010. Brian Peterson /Minneapolis Star Tribune hide caption

itoggle caption Brian Peterson /Minneapolis Star Tribune

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 — pose at the Supreme Court in 2010. Chip Somodevilla/Getty Images hide caption

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President Obama waves after signing the Affordable Care Act at the White House on March 23, 2010. Chip Somodevilla/Getty Images hide caption

itoggle caption Chip Somodevilla/Getty Images

The U.S. Supreme Court on the eve of a hearing about the Florida presidential election recount, Nov. 30, 2000. The justices later ruled 5-4 in the case of Bush v. Gore, effectively deciding the outcome of the presidential race. Alex Wong/Getty Images 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

itoggle caption Paul J. Richards/AFP/Getty Images