WASHINGTON (AP) _ Prosecutors who do not tell the truth when offering justification for an arrest warrant are not always shielded from being sued by innocent people who get jailed as a result, the Supreme Court ruled today.

Voting unanimously in a case from King County, Wash., the court refused to kill a lawsuit by a Seattle-area man who spent a night in jail for a burglary he did not commit.

Past Supreme Court rulings have given the nation's prosecutors immunity from suit when they act _ even dishonestly _ in initiating and prosecuting a criminal case but not when they perform administrative or investigative work.

Justice John Paul Stevens wrote for the court today that King County prosecutors' practice of personally giving ``sworn testimony establishing the grounds for issuing the warrant'' is not always protected.

The practice is not prevalent in other parts of the country, Stevens noted. Most often, police officers give such justification _ and they do not have absolute immunity from being sued.

``Testifying about facts is the function of a witness, not of the lawyer,'' Stevens said.

Rodney Fletcher of Auburn, Wash., was arrested in 1993 and charged with stealing computer equipment from a school in Seattle. The charges were quickly dropped but not before he spent a night in the King County jail.

He later sued Lynne Kalina, a county deputy prosecutor. Fletcher's lawsuit alleged that she had made statements she should have known were false when seeking a court warrant for his arrest.

Kalina filed documents that said Fletcher never had been associated with the school and did not have permission to enter it. She also said someone identified Fletcher as the man who tried to sell computer equipment taken from the school.

In fact, Fletcher had done some construction work inside the school months before the burglary and it was not surprising that his fingerprints were found there. And his lawsuit alleged that no witness linked him to the sale of the stolen items.

Kalina sought to have Fletcher's lawsuit thrown out based on her claim of absolute immunity, but a federal trial judge and the 9th U.S. Circuit Court of Appeals refused to do that.

Today's decision upheld those rulings as the justices rejected King County Prosecutor Norman Maleng's argument that Kalina was performing a prosecutorial duty when filing the sworn statement in support of the arrest warrant request.

Stevens also rejected Maleng's claim that denying absolute immunity in such cases will have a ``chilling effect'' on the administration of justice.

The case is Kalina vs. Fletcher, 96-792.