The American Bar Association today responded to the "not guilty" verdict in the trial of John W. Hinckley Jr. by recommending new restrictions on the use of the insanity defense.

The action brought the association, which represents nearly 300,000 lawyers, into substantial agreement with both the Reagan administration and the American Psychiatric Association, creating a powerful coalition for changing the direction the law has taken for decades.

Sponsors of the change see it as an effort, in part, to head off more extreme measures, such as abolition of the insanity defense.

The ABA's new position reverses a policy it adopted in 1976 and runs contrary to the law as it now operates in half the states, including Maryland, and in most federal jurisdictions, including the District of Columbia.

That approach allows a verdict of "not guilty by reason of insanity" for a defendant who knew he was committing a crime but allegedly could not control his behavior because of mental illness.

Under the new recommendation, if a defendant could appreciate the wrongfulness of his act at the time it was committed, he can be found guilty. Inability to exercise self-control--acting on an "irresistible impulse"--would be no excuse.

Supporters contend that the new standard, if it had applied in the Hinckley trial, would have substantially weakened the defense of the man accused of the attempted assassination of President Reagan.

They also said it would eliminate the most subjective, confusing and inexact elements of testimony in the few trials (less than 1 percent) involving the insanity plea: the conflicting opinions of psychiatrists over whether a defendant had the capacity to control himself.

"We do not have scientific evidence" to make that judgment, Dr. Loren Roth, representing the American Psychiatric Association, told the lawyers before today's vote. The new appproach, he said, will be "more likely to identify only those people with severe mental illness for exculpation."

The ABA did not go as far as many critics would have liked. In addition to opposing abolition of the insanity defense, the association recommended that, where its new standard is adopted, prosecutors should bear the burden of proof.

That means that once a defendant claims an inability to appreciate wrongfulness, the prosecution must introduce evidence sufficient to convince the jury otherwise.

Many observers attributed the Hinckley verdict to the fact that the prosecution had that difficult task, and wanted the law changed. The Reagan administration still supports shifting the burden to make the defense prove insanity, and it withheld support of that part of the ABA recommmendation, although it does support the bulk of the change, according to D. Lowell Jensen, assistant attorney general for the Justice Department's Criminal Division.

The ABA did recommend that the burden of proof be on the defendant in those states that decline to adopt the new standard.

Opponents of today's action, largely delegates from the ABA Criminal Justice Section, said the organization was overreacting to the Hinckley trial.

"Why is there such a rush?" asked William W. Greenhalgh, a Georgetown University law professor and head of the Criminal Justice Section. "We have one notorious case and one case only. Why is there so much activity in such a short time?"

The vote was a repudiation of standards developed by the American Law Institute since the 1950s: a so-called "two-pronged test" involving appreciation of wrongfulness or ability to conform behavior. That test is based on what criticis now say was an overly optimistic assessment of psychiatric capabilities.

We "went beyond the state of the art" in psychiatry, said Justice William H. Erickson of the Colorado Supreme Court.

"I think there is a broad public consensus that you shouldn't punish people who don't know right from wrong," said Bruce J. Ennis, a Washington lawyer, former American Civil Liberties Union attorney and an expert in mental health law who led the fight for the change. "But the public doesn't understand" letting someone off because of "an irresistible impulse."

In other major action today:

* The ABA House of Delegates voted to make gun control a lobbying priority of the association, though it did not change its prior moderate position, which does not include support for a ban on possession of handguns.

* The delegates rejected the call from manufacturers for a broad federal products-liability law.

* The House of Delegates went on record against elevating bankruptcy court judges to the status of U.S. District Court judges.