The decision, still under seal, is a setback for Lewinsky's lawyers, who had maintained that Whitewater prosecutors had a binding agreement not to prosecute the former White House intern in exchange for her cooperation.
Now, Lewinsky's lawyers will have to appeal or seek other avenues to remove their client from the possibility of criminal prosecution.
Her chief lawyer, William Ginsburg, said Wednesday night he had not been informed of the decision.
"I have not seen either, or been informed of the existence of an opinion," Ginsburg said in a telephone interview.
The decision by U.S. District Court Judge Norma Holloway Johnson was confirmed to the AP and other news organizations Wednesday.
The Washington Post reported in today's editions that even though the judge issued a written order last week, she has yet to enter a full, formal ruling outlining the reasoning behind her legal opinion.
The ruling renews a legal and political headache for the White House, which for weeks has been spared the prospect of Lewinsky cooperating with Whitewater prosecutor Kenneth Starr while the court battle over immunity was fought in secret.
Ginsburg has said if he lost the ruling, he would appeal.
But with the court victory, Starr's office could make another effort to secure Lewinsky's cooperation, force her to testify before the grand jury with a grant of limited immunity from a judge, or indict her. Ginsburg has said his client had been informed she was someone likely to be indicted.
Charles Bakaly, a spokesman for Starr, declined comment Wednesday night.
Lewinsky made no comment Wednesday evening as she arrived at her father's home in the Brentwood area of Los Angeles.
Ginsburg had gone to court trying to enforce what he has said was a deal reached in late January with Starr in which his client would be given full immunity for her testimony. Starr denied there was such a deal. Lawyers on both sides had argued the issue before Johnson.
The court battle has caused delays in the investigation into allegations that Clinton had an affair with Lewinsky and urged her to lie about it. Starr had awaited a judge's ruling to decide what action to take with the 24-year-old Lewinsky, who told a Pentagon colleague, Linda Tripp, she had a sexual relationship with the president beginning in November 1995 that lasted 18 months.
In the interim, Starr has called other witnesses before the grand jury seeking to determine if Lewinsky submitted a false affidavit in the Paula Jones sexual harassment lawsuit against Clinton.
In that affidavit, Lewinsky denied having sexual relations with the president. But prosecutors have obtained secretly taped conversations in which Lewinsky confided to Tripp of an affair and a cover-up.
The immunity issue is one of several legal battles taking place behind closed doors, including efforts by the Clinton administration to stop Secret Service officers from testifying and White House aides' refusal to answer certain questions on grounds of executive privilege.
In the absence of Lewinsky's cooperation, prosecutors have brought numerous other witnesses before the grand jury.
Among the matters they are investigating is whether Clinton friend and Washington power broker Vernon Jordan sought to influence Lewinsky's testimony in the Jones case by arranging a job for her in New York and getting a lawyer to help her submit the affidavit.
Clinton and Jordan have denied any wrongdoing.