MINNEAPOLIS — The NFL is asking the U.S. Supreme Court to overturn a decision that allowed Minnesota Vikings defensive linemen Kevin and Pat Williams to challenge their four-game suspensions for violating the league's anti-drug policy.

The NFL cited the National Labor Relations Act in its filing on Thursday, saying its collective bargaining agreement with the players' union protects its drug policy from lawsuits in state courts.

The Williamses, no relation, tested positive in 2008 for a banned diuretic, bumetanide, that was not listed as an ingredient on the label for the weight-loss supplement StarCaps. The diuretic is not a steroid, but the league said it can be used as a masking agent for performance-enhancing drugs and therefore is not allowed.

The players sued to block their suspensions, saying the NFL broke Minnesota labor law in applying its drug policy. The NFL wants the Supreme Court to overturn a federal judge's decision in the 8th Circuit Court of Appeals last year that sent the case to state court.

The NFL wants the case settled on the federal level to overrule the state court proceedings and establish that rules of the CBA are not subject to individual state laws.

"The Eighth Circuit's decision destroys the orderly and predictable negotiation and administration of collective bargaining agreements," lawyers for the NFL wrote in the brief submitted to the Supreme Court.

"The Eighth Circuit's erroneous pre-emption decision thus has turned federal labor law from a uniform and stable framework for labor-management relations into a legal Catch-22 in which employers are literally liable if they do comply with the collective bargaining agreement, and liable if they do not," the brief said.

An attorney for the players, Peter Ginsberg, said he wasn't worried about the appeal.

"We are confident that the 8th Circuit Court of Appeals thoroughly and correctly analyzed the pre-emption issues," he said. "We are also confident that the decision upholding the principle that the NFL is obligated to abide by the law of states where it does business — as are all other multistate entities — is consistent with the jurisprudence and important pillars of our system of justice."

Ginsberg was referring to a decision last week by Hennepin County District Judge Gary Larson, who ruled that the NFL failed to abide to state law in notifying the two players of their positive drug test. Larson, however, concluded that failure wasn't enough to prevent the NFL from suspending the players.

The judge put off a decision on whether to extend an injunction blocking the suspensions pending an appeal by the players. A decision isn't expected until next week.

The case has dragged on for 18 months and the Williamses played last season, helping the Vikings reach the NFC title game in January.

The NFL's brief said remanding the case to state court "created one collectively bargained rule for NFL players in Minnesota and a different rule under the same collective bargaining agreement for all other NFL players."

The NFL and other sports leagues contend that their drug-testing programs would be at risk if state-level challenges like the Williamses were allowed to proceed. Major League Baseball, the National Basketball Association and the National Hockey League all filed briefs in support of the NFL's position. The U.S. Anti-Doping Agency filed a similar motion on its own.

"For national sports leagues, enforcing uniform standards of player conduct is indispensable to ensuring a level competitive playing field," NFL lawyers wrote. "The piece-meal rewriting, state by state, of a national collective bargaining agreement eviscerates the uniformity and even-handedness in player qualifications that are essential to national sports leagues."

Saints defensive end Will Smith and former Saints end Charles Grant tested positive for the same substance, but were not involved in the Minnesota lawsuit. The NFL has held off on enforcing their four-game suspensions until the Minnesota case is resolved. Grant is a free agent after being released by the Saints.