The Supreme Court, in a decision crucial to deregulation of the nation's radio airwaves, ruled yesterday that radio stations can change their program formats without interference from the Federal Communications Commission.

The court ruled 7 to 2 that "market forces," not the federal government or the courts, should be allowed to determine the kind of music and talk that radio stations air. The justices rejected pleas by classical music fans and minority groups upset because programs tailored for them have been replaced by more commercially successful formats around the country.

In the process the justices resolved a six-year-old struggle between the FCC, which did not want to regulate program format, and the U.S. Court of Appeals for the District of Columbia, which had ordered the agency to do it anyway, by reversing the appeals court in no uncertain terms.

"Our opinions have repeatedly emphasized that the commission's judgment regarding how the public interest is best served is entitled to substantial judicial deference," Justice Byron White wrote for the court.

The court's decision involves entertainment broadcasting only; the FCC retains the right to regulate in other areas, as, for example, through its fairness doctrine for news programs.

The regulatory dispute involved dozens of parties. On the one side was the FCC and a united front of virtually every major radio broadcast corporation in the United States. On the other were dozens of classical music fan clubs, ethnic organizations, eight or nine states and the United Church of Christ.

Ethnic groups argued that foreign language broadcasts were in jeopardy. Classical music clubs said that their preferences were being ignored by stations seeking mass audiences by playing tops in pops or rock in markets where there were already stations playing that music.

The fight began in 1969 when a station in Atlanta made a format change from classical music to a blend of lighter music. When the station's license was up for renewal (as all are every three years), classical music fans urged the FCC to oppose the format change on the grounds that the new programming duplicated what other Atlanta stations were playing and removed the only classical station from the area. The FCC declined but was reversed by the federal court.

In 1973, classical groups met FCC resistance when they challenged a similar change by a radio station in Chicago and when they objected to the switch from classical music by station WNCN in New York.

The FCC argued that First Amendment free-speech guarantees precluded interference with such format changes when licenses were renewed or when stations changed hands. The agency also said it would be an administrative impossibility to review listeners' preferences in every market in judging a station's format plans.

The groups, headed by the WNCN Listeners Guild in New York, nevertheless won a ruling from the appeals court in Washington requiring the FCC to hold hearings on such format changes when there was "significant public grumbling" about the elimination of "unique formats.

The FCC continued to resist the Court of Appeals, however, issuing its own statement of policy in 1976 that was directly contrary to the court's rulings. Lawyers for the WNCN Listeners Guild called the FCC's action an "entirely unorthodox and essentially illegal enterprise."

The justices disgreed yesterday. "The FCC seeks to further the interests of the listening public as a whole by relying on market forces to promote diversity in radio entertainment formats and to satisfy the entertainment preferences of radio listeners," White wrote. "This policy does not conflict with the First Amendment."

The law does not require radio broadcasters "to seek permission to make format changes" when licenses are not up for renewal or at transfer to new owners, White said. And it does not require such permission when the licenses are up, as the court of appeals ruled.

Congress, in 1927, expressly prohibited censorship and other "interference with free speech" in radio in the Communications Act. While that does not mean that Congress meant to prohibit format review, the interpretation of the law should be left to the federal agency charged with interpreting "unless there are compelling indications that it is wrong," the court said.

Justices Thurgood Marshall and William Brennan dissented from yesterday's ruling in FCC et al. vs. WNCN Listeners Guild et al. The Court of Appeals "format doctrine," Marshall wrote, "was a permissible attempt to provide the commission with some guidance regarding the types of situations in which a reexamination of general policy might be necessary."

In other action yesterday:

The court settled a dispute between the state of Montana and the Crow Indians over hunting and fishing rights on the reservation. The court ruled that the state, not the tribe, owns the Big Horn River Flowing through the reservation. Thus the state, not the Indians, has the power to regulate hunting and fishing on the river.

The court failed for the second year in a row to answer the question of how far land use regulations can go before constituting an unconstitutional seizure of private property. The case was brought by the San Diego Gas and Electric Co., after land it owned was classified as open space, thus preventing development. The company appealed unsuccessfully through the California courts, with the California Supreme Court ruling that monetary compensation was not an appropriate remedy for the company.