President Reagan yesterday vetoed legislation to make permanent the nearly 40-year-old "Fairness Doctrine" rule that broadcasters have condemned as a violation of their First Amendment rights.

"This type of content-based regulation by the federal government is, in my judgment, antagonistic to the freedom of expression guaranteed" by the Constitution, Reagan said in his veto message. He noted that the Federal Communications Commission has opposed its own rule.

"In any other medium besides broadcasting, such federal policing of the editorial judgment of journalists would be unthinkable," he said. "The framers of the First Amendment, confident that public debate would be freer and healthier without the kind of interference represented by the 'Fairness Doctrine,' chose to forbid such regulations in the clearest terms," he said.

Reagan cited the constitutional language ordering that Congress "shall make no law . . . abridging the freedom of the speech, or of the press."

More recently, he noted, the Supreme Court struck down a "right-of-access" statute -- a sort of fairness doctrine for newspapers. Reagan said the court had criticized "the statute's intrusion into the function of the editorial process."

The Fairness Doctrine requires radio and television broadcasters to cover issues of public importance and present opposing views.

It has been FCC policy since 1949, but a federal appeals court last fall ruled that it was not a law and could be repealed by the FCC.

The FCC says the policy is constitutionally suspect because it gives the government a measure of editorial control over the broadcast media. The agency also says the policy inhibits coverage of controversial issues because broadcasters fear lawsuits and license challenges.

Opponents also say the doctrine is no longer necessary to ensure that all views on an issue be aired because of the large number of alternative information sources available to the public, including more than 10,000 radio stations, nearly 1,600 television stations and about 7,700 cable television systems.

But supporters maintain that unlike the print media, which is not subject to the policy, radio and television stations are using a limited public resource -- the electromagnetic spectrum -- and that the doctrine is necessary to ensure that minority viewpoints are aired.

The measure was passed by the House 302 to 103 and the Senate, 59 to 31. Sen. Bob Packwood (R-Ore.) is leading the effort in the Senate, with help from the administration, to line up enough votes to prevent an override of the veto. Even if Packwood succeeds, key supporters have said they will reoffer the measure as an amendment to other bills.