Preservationists and lawyers representing the owners of the Warner Theater -- antagonists in a long-simmering feud over the building's fate -- each claimed partial victory last week after a federal judge set aside the designation of the building's exterior as a historic landmark but refused to declare the landmark designation process unconstitutional.

U.S. District Court Judge Louis F. Oberdorfer ruled Wednesday that a D.C. agency had acted in an "untimely and unlawful" manner by failing to stick to a 90-day limit in declaring the exterior a historic landmark after the building owners challenged that designation.

But he left the door open to landmark status for the building's interior by rejecting arguments that the landmark designation process violates the constitutional rights of the owners.

The District of Columbia Preservation League has sought since 1981 to preserve the Warner Building at 13th and E streets NW, calling it the last example of "the old downtown movie palaces," with its ornate, Classical Revival interior.

William Taylor, who represents the building owners, pointed to the judge's decision to set aside the exterior landmark status and said, "It certainly created a break in the clouds that was a long time in coming." The building facade was declared a landmark in 1983.

Kim Hoagland, an architectural historian and a league official, said the judge's opinion nevertheless "upheld the whole preservation process by saying that the owners' due process rights were not violated."

Oberdorfer also declared that the owners must "maintain the status quo . . . particularly with respect to any alteration or demolition of the building" pending further rulings in the case.

"This is only preliminary," said deputy corporation counsel James Murphy, who represents the District. "A lot of other things are going to happen," he said, adding that the District still must determine if it will appeal the judge's ruling.

According to the opinion, the Joint Committee on Landmarks of the National Capital violated District statutes by failing to act promptly on the preservationists' application to declare the building facade a landmark.

Once that application is filed, the building must be treated as a landmark until a decision is made, according to the judge's opinion. Because of that, owners must "make a special showing of public interest or economic hardship" in order to obtain a permit to alter the building.

To protect owners' rights, the statute gives the landmark agency 90 days to make its decision once an owner seeks to alter the building, according to the opinion.

In the Warner case, the agency took nearly six months to decide. The preservationists had filed for landmark status in April 1981. The owners sought a permit to alter the building's doorway in November 1982, but the agency did not act on the issue until May 18, 1983.

Oberdorfer vacated the landmark designation but left the door open for the preservationists to file a new application.

On the issue of the landmark designation process, Oberdorfer found that it places a burden on building owners that is "not negligible." In this case, he said that the process "played a role in the disruption" of a plan to sell the building in 1982. But, he ruled, the burden "does not rise to constitutional proportions."

There is also a dispute as to the owners' plan for the 10-story building, which houses the theater and, on the upper floors, offices. Attorney Linda Powers, who represents the preservationists, said the owners plan to gut the interior and make it into an office building.

Attorney Taylor said yesterday he was not certain what the owners' plans are. Offices, he said, "are an obvious possibility given the location . . . . We want the right to develop the building as we see fit, to evaluate the various alternatives without the landmark designation."