The Supreme Court yesterday left intact a Federal Communications Commission decision that could dramatically affect the future of sports broadcasting.

The justices rejected an appeal by the National Football League, which wanted the court to prohibit cable television systems from offering a Sunday gridiron smorgasbord of "up to a dozen NFL games."

The NFL was upset at an FCC decision relaxing "distant signal rules," which had served to limit the number of out-of-town television stations a cable system could offer in a particular area.

The NFL argued that the resultant programming blitz would unfairly compete with attendance at home games. The basic structure of professional football was at stake, it claimed.

"If not restricted by regulation, a cable system could bring into an NFL team's home territory, when the team is playing a home game on a Sunday, every NFL game being played that day," the league complained.

In other action yesterday:

The court agreed to review a District of Columbia case raising the question of how long someone may be confined to St. Elizabeth's Hospital after an insanity plea in a criminal case. The case involves Michael A. Jones, who has been confined at St. Elizabeth's for six years after pleading not guilty by reason of insanity to the theft of a coat from a department store.

Jones' lawyers argued that the continued confinement is unconstitutional because it has exceeded by five years the maximum punishment for the theft. Jones was held after the hospital determined that he was a paranoid schizophrenic dangerous to himself and society.

The court handed thousands of shipyard workers a potentially major victory in their attempt to collect money for injuries caused by exposure to asbestos. The court let stand a ruling that could let many of the workers invoke federal admiralty law in their suits against asbestos manufacturers. There are thousands of pending lawsuits alleging fault by the manufacturers for failure to warn shipyard workers and others of the potential danger from asbestos, which has been linked to a number of serious diseases, including lung cancer.

The court agreed to take a look at "moral nuisance" laws used by states and cities to control obscene material by shutting down adult bookstores and theaters. The case facing the court is an appeal by owners of two Idaho bookstores contesting a ruling that closed their business for a year for selling "lewd publications."

The justices left intact a ruling that allows the president and attorney general to authorize warrantless electronic surveillance to gather foreign intelligence information.

The court agreed to consider an Illinois case testing the legal value of anonymous tips received by police departments. The justices will decide whether a detailed, anonymous tip, corroborated by other law enforcement information, provides a sufficient basis to issue a search warrant.

The court agreed to decide whether blacks and Hispanics laid off the New York City police force as a result of low job test scores must prove intentional discrimination.The 2nd U.S. Circuit Court of Appeals ruled that the minority officers had to show more than that Civil Service examinations had a disproportionately negative impact on blacks and Hispanics. The officers must prove "discriminatory intent" to obtain relief under certain job discrimination laws, the court ruled. The dispute stems from a June, 1975, layoff of 2,800 New York police officers, of which 21.5 percent were minorities.