The Supreme Court on Monday struck down a federal law that bars gambling on football, basketball, baseball and other sports in most states, giving states the go-ahead to legalize betting on sports.The Supreme Court ruled 6-3 to strike down the Professional and Amateur Sports Protection Act. The 1992 law barred state-authorized sports gambling with some exceptions. It made Nevada the only state where a person could wager on the results of a single game.The court said the federal law violated constitutional principles limiting the federal government from controlling state policy, unconstitutionally forcing states to prohibit sports betting under their own laws."The legalization of sports gambling requires an important policy choice, but the choice is not ours to make," Justice Samuel Alito wrote. "Congress can regulate sports gambling directly, but if it elects not to do so, each state is free to act on its own."One research firm estimated before the ruling that if the Supreme Court were to strike down the law, 32 states would likely offer sports betting within five years.The court's decision came in a case from New Jersey, which has fought for years to legalize gambling on sports at casinos and racetracks in the state.The controversy started in 2011, when New Jersey voters approved a measure to legalize sports betting to help the casino industries in a faltering economy. But the state law was immediately challenged by professional sports leagues and the NCAA, which pointed to a federal law passed in 1992 that bans state sports betting with some exceptions.More than a dozen states had supported New Jersey, which argued that Congress exceeded its authority when it passed the 1992 Professional and Amateur Sports Protection Act, barring states from authorizing sports betting. New Jersey said the Constitution allows Congress to pass laws barring wagering on sports, but Congress can't require states to keep sports gambling prohibitions in place.All four major U.S. professional sports leagues, the NCAA and the federal government had urged the court to uphold the federal law. In court, the NBA, NFL, NHL and Major League Baseball had argued that New Jersey's gambling expansion would hurt the integrity of their games. Outside court, however, leaders of all but the NFL have shown varying degrees of openness to legalized sports gambling.The American Gaming Association estimates that Americans illegally wager about $150 billion on sports each year.The American Gaming Association said in a statement that Monday's ruling makes it possible for states and sovereign tribal nations to give Americans what they want: an open and a transparent and responsible market for sports betting.The association said it stands ready to work with governments, sports leagues and others to create a new regulatory environment.The 1992 law at issue in the case bars state-authorized sports gambling with exceptions for Nevada, Montana, Oregon and Delaware, states that had approved some form of sports wagering before the law took effect. Nevada is the only state where a person can wager on the results of a single game, though the law doesn't cover wagering between friends. The law also doesn't cover animal races, such as horse racing, which many states already allow.New Jersey has spent years and millions of dollars in legal fees trying to legalize sports betting at its casinos, racetracks and former racetracks. In 2012, with voters' support, New Jersey lawmakers passed a law allowing sports betting, directly challenging the 1992 federal law which says states can't "authorize by law" sports gambling. The four major professional sports leagues and the NCAA sued, and the state lost in court.In 2014, New Jersey tried a different tactic by repealing laws prohibiting sports gambling at casinos and racetracks. It argued taking its laws off the books was different from authorizing sports gambling. The state lost again and then took the case to the Supreme Court.Professional sports leagues weigh inThe NFL plans to ask Congress "to enact a core regulatory framework for legalized sports betting" following the Supreme Court's ruling.In its statement, the NFL noted that "Congress has long recognized the potential harms posed by sports betting to the integrity of sporting contests and the public confidence in these events."The NFL also said it will work closely with teams to ensure that any state proposals "protect our fans and the integrity of our game."NBA Commissioner Adam Silver says the pro basketball league remains in favor "of a federal framework that would provide a uniform approach to sports gambling in states that choose to permit it." He said that "regardless of the particulars of any future sports betting law, the integrity of our game remains our highest priority."Tony Clark, the head of the Major League Baseball Players Association, calls the Supreme Court's ruling on sports betting "monumental, with far-reaching implications for baseball players and the games we love."Clark said the topic must be addressed "urgently and thoughtfully to avoid putting our sport's integrity at risk as states proceed with legislation."New Jersey Gov. Phil Murphy and former Gov. Chris Christie are praising the Supreme Court's ruling.Murphy, a Democrat, says he's thrilled and credited the court victory to Christie, who is his predecessor.Monmouth Park racetrack has already established a sports betting facility and said it plans to take bets "as soon as possible."Dennis Drazin, the chairman and CEO of Darby Development LLC, which operates the track, says the ruling could help the state's struggling horse racing industry.___Follow Jessica Gresko on Twitter at http://twitter.com/jessicagresko