A federal judge said yesterday that the Ku Klux Klan has a clear constitutional right to march Sunday in Washington and ordered District police officials to grant it a permit to parade along an 11-block section of Constitution Avenue.

U.S. District Judge Louis F. Oberdorfer spent almost two hours questioning District and federal lawyers about how they would fulfill their obligation to maintain order along a downtown parade route.

Last night, hours after leaving the hearing, Oberdorfer issued his ruling on the American Civil Liberties Union's request for a temporary restraining order or a preliminary injunction to clear the way for the Klan's march.

The ACLU filed suit because neither the National Park Service nor the District government had issued a permit for seven blocks of the planned march. The Klan has a permit to assemble at the Washington Monument, march along four blocks of Constitution Avenue and rally at the Capitol.

Outside court, Klan leader Virgil Griffin had just finished saying he was willing to die for his constitutional rights when a man passing by in a security guard's uniform called out, "You damn sure won't march in Washington."

"Damn sure will march in Washington," Griffin shot back as the man was hustled away by courthouse security officers.

Oberdorfer's ruling means that D.C. police will have the task of trying to protect Griffin and 50 followers from several thousand expected counter-demonstrators who have vowed to stop the Klan from marching.

The same Klan group, from Mount Holly, N.C., was prevented from marching on Constitution Avenue on Labor Day weekend when 3,000 demonstrators massed along the route, injuring 12 officers and blocking the street.

The route approved by Oberdorfer, which was the first choice of the Klan, begins on federal land and moves onto Constitution Avenue at 14th Street, in D.C. police territory. District police said in court that they could not provide security over that much of Constitution Avenue.

Another route that was considered by the judge includes seven blocks of Madison Drive on the Mall, under the jurisdiction of the U.S. Park Police. The National Park Service had not issued a permit for that route because the 500-officer force cannot provide enough security, and D.C. police officials have refused to join them on the Mall before the march begins.

Last night, ACLU lawyer Arthur Spitzer said he was "delighted with the decision because it was a real vindication for the First Amendment."