JEFFREY TOOBIN, a young lawyer in New York, won a big victory in federal court there on Thursday. He was not the attorney of record in the case, but the plaintiff. He sued the formidable Lawrence Walsh, independent counsel in the Iran-contra cases, and won hands down. The dispute is about a book Mr. Toobin has written detailing his own experiences as a member of the Oliver North prosecution team. He was a very junior member of that team -- only 26 at the time -- but his publishers claim that he has produced an insider's account of one of the most famous trials of the decade.

During his employment at the Office of Independent Counsel, Mr. Toobin signed a series of agreements relating to the disclosure of classified information on certain materials relating to the investigation. As an attorney, he is also bound not to disclose grand jury material. Acknowledging these obligations, the author submitted first individual chapters and then his entire manuscript to the OIC, the Justice Department and the CIA. The latter two agencies found no reason to block publication, but Mr. Walsh strongly opposed it. Over the course of 18 months, he filed objections, complained to the Justice Department, threatened the author with professional disciplinary action and even intimated that Mr. Toobin would be prosecuted criminally. Finally, the fledgling writer and his publisher took the offensive and went to court for a declaratory judgment stating that publication would not violate any of the non-disclosure agreements or grand jury secrecy rules Mr. Walsh had invoked. He won that ruling, and with it the right to publish with a clear conscience, from Judge John Keenan last week.

Mr. Walsh is a distinguished and respected attorney who came out of retirement to take on the burden of the Iran-contra prosecutions. He has performed this great public service for more than four years. But he made a mistake in trying to quash his young assistant. Even Judge Keenan couldn't understand what all the fuss was about. Any request for prior restraint of publication, he reminded the parties, "comes to this court bearing a heavy presumption against its constitutional validity." The material in question in this case is mostly based on material already well-known to the public through the nationally televised congressional hearings, the reports of congressional and independent committees and the trials. Mr. Toobin's own account of his experience, his interpretation of events and his anecdotes about personalities will all be new to the public but certainly pose no threat to national security or the continuing appeals in Iran-contra cases.