This week's verdict in the case of John W. Hinckley Jr. has cleared the way for action on three lawsuits seeking a total of $72 million in damages from him for three victims of Hinckley's assault on the president.

Lawyers for Secret Service agent Timothy J. McCarthy and retired D.C. policeman Thomas K. Delahanty, both wounded in the March 30, 1981, shooting, said yesterday the civil suits could result in another jury being asked to decide whether Hinckley was insane at the time of the shooting.

If the civil cases reach jury trial, the lawyers said, the burden would shift to Hinckley's defense team to prove he was insane, unlike the rules of the just-concluded federal criminal case in which the prosecution had the burden of proving Hinckley sane.

"The shoe is now on the other foot," said Paul D. Kamenar, director of litigation for the Washington Legal Foundation, which represents McCarthy, "In a criminal case, you had a presumption of insanity and the prosecution had the burden. On the civil side, he walks in with a presumption of sanity . . . and the burden is now on him . . . . It's a whole new ballgame."

However, both Kamenar and Robert Cadeaux, who is Delahanty's lawyer, said they are unsure whether the case will reach trial on the psychiatric questions. U.S. District Judge John G. Penn would first have to determine whether insanity can be used as a defense in the suit, a point which is unclear from past decisions, according to Cadeaux.

Penn is hearing all three civil cases against Hinckley, including a $46 million suit filed by White House press secretary James Brady. All three suits were filed months ago, but Penn ruled that there would be no action on them until the conclusion of Hinckley's criminal trial.

Hinckley's lawyers would not comment on the suits yesterday, but in their response to the suits in U.S. District Court, they argue that his "insanity on March 30, 1981" prevents him from being held liable for injuries he inflicted. His insanity, they said, meant that he did not intend to hurt the plaintiffs and therefore cannot be made to pay for their suffering.

Delahanty, who was struck in the shoulder and neck by a bullet and lost partial use of his arm, is seeking $12 million in damages, while McCarthy, who cited damage to his lung, diaphragm and liver, is seeking $14 million. Delahanty, 45, a 17-year veteran of the police force, retired because of his injuries and lives in Beltsville with his wife Jean, who is a coplaintiff. McCarthy, 31, has returned to duty with the Secret Service.

Brady, 40, suffered the most severe injuries of the four persons shot outside the Washington Hilton. He is still recovering from a gunshot wound to the brain which is expected to have lasting effects.

After his arrest Hinckley said in court that he had no property or bank accounts, and he was declared indigent by a U.S. magistrate. His father, John W. Hinckley Sr., is chairman of the board of Vanderbilt Energy Co. in Denver, an oil and gas exploration firm. His parents retained the law firm of Williams & Connolly on his behalf.

Lawyers for Brady, McCarthy and Delahanty said they intend to discover whether the younger Hinckley has insurance policies, Vanderbilt stock, or trust funds in his name that could be tapped in the event of a civil judgment against him. Kamenar also said he intends, through depositions, to attempt to learn more about the Hinckley family finances in an effort to find sources of money that the wounded parties might seek.

Yesterday the Washington Legal Foundation, a nonprofit public interest law center that often represents government officials and crime victims, filed a notice in District Court saying lawyers for McCarthy intended to question Hinckley at St. Elizabeths Hospital on July 26.

Kamenar said he intends to ask Hinckley "many of the questions he would have answered" if he had testified in his defense. Hinckley never took the stand in his criminal trial. Hinckley's lawyers are expected to fight Kamenar's effort to question their client.

Last Monday's verdict that Hinckley was not guilty by reason of insanity does not necessarily carry over to civil matters, Cadeaux said.

He said past civil cases dealing with insanity have yielded contradictory results. But he added that insanity could be treated similarly to alcoholism in assessing responsibility. "An alcoholic has an accident at the wheel, drunk. Though it is an illness, alcoholism doesn't forgive an act of negligence. Although Hinckley may suffer mental illness, it does not forgive him of his civil responsibility," he said.

If the court found that Hinckley, because of his mental state, had not intended to harm his victims, he would probably not be held liable for punitive damages, Cadeaux said. However, Hinckley could still be held liable for compensatory damages for the persons he hurt, he said.