The judge in the Iran-contra trial of John M. Poindexter yesterday refused to overturn the former national security adviser's conviction and held "there is no evidence" that former president Ronald Reagan authorized Poindexter or other aides to violate the law.

In rejecting a defense request to either set aside last month's jury verdict or order a new trial, U.S. District Judge Harold H. Greene found that the prosecution's case against Poindexter was "compelling" and that the defense "was neither broad nor particularly convincing."

Greene said the "relative weakness of the defense appears to have been due to the fact" that neither Reagan nor former National Security Council aide Oliver L. North Jr. was "willing to relieve {Poindexter} of culpability."

"And . . . other than to attempt to weaken the testimony of the {prosecution's} witnesses through cross examination, Poindexter simply did not have a defense of his own," the judge said in an 85-page opinion.

The jury convicted Poindexter of five felonies, including conspiring to deceive Congress and obstructing and lying during congressional inquiries about secret White House aid to the Nicaraguan contras and the U.S. role in a politically embarrassing 1985 transfer of arms to Iran.

Poindexter is scheduled to be sentenced Monday and faces a maximum sentence of 25 years in prison and a fine of $1.25 million.

A major contention of Poindexter's defense was that the actions for which he was indicted were authorized by Reagan, and that Reagan, like Poindexter, did not think that what he did violated the law. Poindexter's lawyers also argued that the retired Navy rear admiral never intended to mislead Congress.

The chief prosecution witness against Poindexter was North, who reluctantly gave damaging evidence against his former superior. The defense relied heavily on Reagan, who gave videotaped testimony that was played for the jury.

Greene said Reagan testified "credibly" and "under oath" that he did not authorize Poindexter or any other aides to lie to Congress or commit other illegal acts.

Greene said Reagan's "deep concern" both for supporting the contras during a two-year congressional ban on U.S. military aid to the rebels and for the release of Americans held hostage in Lebanon may have caused aides to believe they could violate the law.

"However," Greene wrote, "there is . . . no evidence to contradict the former president's testimony that he warned his subordinates against acting outside the law."

Greene also rejected a defense request that he conduct a post-trial hearing to examine whether the prosecution's case was influenced by testimony Poindexter gave to Congress under a grant of immunity.

The judge also said that a defense claim that he made made biased statements during the trial against Poindexter "entirely lacks merit."