The metro bus and rail system must accept advertisement on a wide range of controversial political and social topics or else accept no ads at all on such issues, a federal judge here ruled yesterday.

Metro officials said they would not appeal the ruling, which lawyers said expanded the First Amendment principles govering other cases involving advertisements on public transportation.

The Supreme Court has ruled, for example, that a municipal transit system can bar all political advertising. In yesterday's ruling, U.S. District Judge John H. Pratt said Metro officials could have done the same. It was Metro's selectivity that was unconstitutional, the judge ruled.

Pratt's ruling came in a case involving an attempt by the Gay Activists Alliance of Washingyon, D.C., Inc., to place a prohomosexual ad inside Metro vehicles.

Metro twice rejected the advertisement in 1978 on the basis of regulations that said it can ban ads that might be "objectionable to a substantial segment of the community . . ." The gay groups with the aid of the American Civil Liberties Union then filed suit contending that the Washington Metropolitan Area Transit Authority regulations violated the First Amendment to the Constitution.

Pratt said Metro's rejection of the ads reflected the "personal and subjective reactions of decision-makers," and was therefore unconsititutional.

"Although we are sympathetic to [Metro's] interests in raising advertising revenue and its natural desire to protect its riders from offensive messages, and to avoid public controversy, we are nevertheless compelled to hold that [Metro] has run counter to the requirements of the First Amendment in its pursuit of these interests and desires," Pratt said.

The attorneys for the gay group argued that Metro, a public agency, was in a different position, since it had already accepted advertisements for pronuclear groups, small religious organizations, Communist Party candidates antiabortion groups, and -- as Judge Pratt noted in his opinion -- "even . . . Madame Bogard, a soothsayer."

In doing so, Pratt said, Metro "created a forum" for a rather broad range of political and social advertising.

"Many riders will undoubtedly take umbrage" at the ad's message. Pratt said, but he concluded that Metro could not ban such ads under the First Amendment once it had accepted others.

The advertisement depicts what appears to be a family photo album superimposed with pictures of "very happy" individuals and couples of the same sex. The ad states "Someone in Your Life is Gay," and is indentified as being sponsored by the Gay Activist Alliance.

Franklin Kameny, a gay activist, said the purpose of the ad was to "generally get across in a tasteful way that we [gays] are everywhere and we're not really the monsters we're supposed to be."

The gay group first tried in March 1978 to get Metro to accept the ad under a free or public interest advertising rate, but it was rejected. Six months later, the group had raised about $5,000 to pay for the advertisement under commerical rates but it was again rejected by the Metro agency.

ACLU attorney Ralph Temple said he was very pleased by the opinion because the court resisted what temple called Metro's "temptation to cut little holes in the Constitution."

John R Kennedy, general counsel for Metro said, "my general inclination is not to appeal it [the ruling]. I think it's a well-reasoned opinion." The Metro board will make the final decision about any appeal.

Kennedy said Metro's regulating governing advertising were merely an attempt to filter out possibly objectionable ads and did reflect a "matter of judgment" on the part of Metro officials.Since the judge ruled the guidelines were vague, Kennedy said, it is unclear what guidelines might be applied in the future.

Although Pratt found that Metro had violated the Constitution, he did rule in Metro's favor that it was not bound by the D.C. Human Rights Act.

That act bars the denial of public facilities "based on sexual orientation." But Pratt said Metro was an interstate agency and therefore the city law did not apply.

Kameny, meanwhile, said "We are very much looking forward to seeing the posters on our Metrobuses." CAPTION: Picture 1, JUDGE JOHN H. PRATT . . . "many rider will take umbrage" Picture 2, Gay activist group has won right to post this advertisement aboard Metro. Copyright (c) 1979. Dirk J. Barker and Gay Activists of Washington. D.C.