San Francisco ? Supreme Court Justice Anthony M. Kennedy said Saturday that prison terms were too long and that he favored scrapping the practice of setting mandatory minimum sentences for some federal crimes.

“Our resources are misspent, our punishments too severe, our sentences too long,” Kennedy told the annual meeting of the American Bar Assn., his remark met by long applause.

“I can accept neither the necessity nor the wisdom of federal mandatory minimum sentences,” Kennedy said. “In all too many cases, mandatory minimum sentences are unjust.”

Kennedy is a moderate conservative placed on the court by President Reagan. Kennedy’s criticism puts him at odds with Atty. Gen. John Ashcroft, who wants prosecutors to closely monitor which judges impose more lenient sentences than federal guidelines recommend. Such oversight, critics say, could limit judicial independence.

Kennedy said he agreed with the need for federal sentencing guidelines. The 15-year-old system gives judges a range of possible punishments for most crimes and eliminates some of the disparities in terms imposed by different judges for the same crime.

Still, the guidelines lead to longer prison terms than were common before, Kennedy said.

“We should revisit this compromise,” he said. “The federal sentencing guidelines should be revised downward.”