A federal appeals court ruled yesterday that owners of National Football League teams have a right to own interests in other professional sports teams, including the ailing North American Soccer League.

The 2nd U.S. Circuit Court of Appeals in Manhattan concluded that the NFL's ban on cross-ownership, imposed in 1978 to counter rising competition from the NASL, was anticompetitive and violated antitrust laws.

The opinion, written by Judge Walter R. Mansfield, said that the league should not be considered as a "single economic entity" in this case and that the antitrust laws apply in cases where there is "a plurality of actors."

The appeals court sent the case back to the district court to determine the amount of damages to be awarded the NASL. The appeals court directed that an injunction be issued against enforcement of the NFL cross-ownership ban.

"We have always believed that it was improper for the NFL to deny those NFL owners who had approached the NASL concerning the acquisition of a NASL franchise from pursuing those ownership interests," said NASL Commissioner Phil Woosnam. "I fully expect that the decision will encourage NFL owners and, for that matter, owners of other sports teams, to renew their interest in the acquisition of NASL franchises."

The NFL said in a prepared statement that, "we certainly intend to appeal this decision. We feel it is simply the latest example of the utter confusion existing among federal courts regarding the way the antitrust laws are applied to professional sports leagues."

One of the harshest critics of the ban on cross-ownership has been Edward Bennett Williams, owner of the Baltimore Orioles, who also is president of the Washington Redskins and owns 14.3 percent of their stock. Under the NFL rule, Williams was not allowed to be the chief operating officer of the Redskins because of his baseball ownership.

"Im'm no surprised," Williams said last night. "I thought the courts would find it violated the law. It's something I've been crying in the wilderness about. It doesn't mean anything for me personally, but I think now cross-ownership prohibitions are over. Anyone who wants to buy into baseball from football can. I think you'll see some ownership changes."

Of the NFL's likely appeal, Williams said: "I suppose they could ask the Supreme Court to take it, but the court only takes about one in every 100 cases. It doesn't seem very likely."

In San Francisco, an attorney for Al Davis, owner of the Oakland Raiders, said that, because of the New York ruling, he will file a motion next week asking for a summary judgement in the case involving Davis' attempt to move the Raiders to Los Angeles.