President Reagan sent legislation to Congress yesterday that would abolish the plea of innocent by reason of insanity as it was used in the trial of presidential assailant John W. Hinckley Jr.

White House officials said Reagan's proposal to restrict the insanity defense sharply was not sparked by the verdict acquitting Hinckley of shooting the president and three others March 30, 1980. But they acknowledged that Hinckley would not have met the insanity test in Reagan's proposal.

The president also asked Congress to scale back the number of cases in which a conviction can be voided because evidence was improperly obtained by police. And Reagan proposed limiting appeals to federal courts from those convicted in state courts.

"These measures will simplify the justice system and make it more likely that those who commit crimes pay a price," Reagan said in a brief appearance in the White House press room. He had discussed the proposals last Saturday in his radio message from Camp David.

Although congressional liberals and conservatives are interested in modifying the insanity defense, time is running out for action in this session, and no action is expected on Reagan's other proposals until the 98th Congress convenes in January.

But a senior administration official said the Reagan package, offered less than two months before Election Day, "gave the president an opportunity to make some points he feels strongly about."

While polls show crime is uppermost on the minds of many Americans, it is also widely recognized as a local problem. Reagan's proposals would apply only to federal criminal cases, but administration officials said they hope to provide a "model" to the states, which have jurisdiction over most violent crimes.

Responding to the Reagan initiative, John Shattuck, national legislative director for the American Civil Liberties Union, said the proposals raise "very serious constitutional questions" and will have "very little if any positive effect on crime in this country."

A White House statement said Reagan intends to "effectively eliminate the insanity defense to the maximum extent permitted by the Constitution."

Associate Attorney General Rudolph W. Giuliani told reporters that the proposal would narrow the definition of insanity so that it would apply only "in a situation where a person didn't know what they were doing, someone who had the mental age of a 2-year-old or believed they were shooting at a tree when in fact they were shooting at a human being."

"It would not apply," Giuliani said, "in the vast majority of cases where it is now used, which are cases where people can't control their behavior, they had an irresistible impulse."

Such a defense was used by Hinckley, who said in a letter to Newsweek magazine this week that the insanity defense exists because this is "a compassionate and fair country . . . sending John Hinckley to a mental hospital instead of prison is the American way."

Under Reagan's proposal, the prosecution in federal courts would still bear the burden of proof in insanity cases -- having to prove, as was required in Hickley's case, that the defendant is sane. However, the grounds for what constitutes sanity would be drastically narrowed.

Guiliani said Reagan's approach would severely limit the parade of psychiatrists who testify in cases involving the insanity defense. Instead, insanity would be a factor in sentencing.

Senate Judiciary Committee Chairman Strom Thurmond (R-S.C.) is expected to introduce modifications to the insanity defense this week, aides said, but his proposal will not be as restrictive as that sought by Reagan.

Reagan also proposed limiting use of the exclusionary rule, which provides that evidence improperly obtained by police cannot be used in criminal proceedings. The bill would allow evidence to be used in cases where the police had "reasonable and good faith" to believe they were acting lawfully.

"The exclusionary rule has never helped an innocent person," said White House counselor Edwin Meese III, a former California county prosecutor instrumental in framing Reagan's anti-crime initiative.

"The only type of people helped by the exclusionary rule are necessarily guilty people because it reverses convictions where they have already been proven guilty," he said.

Reagan also asked Congress to impose a one-year limit on appeals to federal courts of state convictions. This would halt "endless opportunities to second-guess state court judges and juries," the White House said.