A public interest law group filed suit in federal court yesterday, asserting that Arlington County judges have illegally confined at least 290 persons to mental hospitals in the last two years.

The class action suit, filed in U.S. District Court in Alexandria by the Washington-based Mental Health Law Project, a nonprofit, public interest law firm, seeks what project lawyers say would be a landmark decision granting new hearings to all Arlington residents currently involuntarily committed to mental institutions.

Robert Plotkin, the project lawyer who filed the suit, said that between 40 and 60 of the 290 persons are still confined and could be affected by the outcome.

The suit accuses three Arlington General District Court judges, a magistrate and Virginia Commissioner of Mental Health and Mental Retardation Leo E. Kirven Jr. of failing to grant proper hearings in accordance with Virginia's committal laws, which were substantially toughened in 1976.

The suit says that in 92 percent of the 290 cases, commitment hearings were held on such short notice that those committed were unable to prepare a defense.

It also asserts that court-appointed lawyers representing those committed failed to protect their clients' rights. In 85 percent of the cases, the suit claims, the court appointed the same pair of physicians to examine the defendant, although neither physician had psychiatric training and both are general practitioners.

The suit says that in 77 percent of the cases, the examining physician failed to complete a state-required commitment form properly, most often failing to certify whether commitment was even necessary.

The suit was filed on behalf of two anonymous Arlington residents indentified only as Virginia Woe and Jane Doe.

In Woe's case, the suit asserts, Arlington police took her to a court hearing barefoot, handcuffed and in her nightgown on Sept. 15, 1976, the morning her sister filed a petition to confine her to a mental hospital.

The suit cliams that the physician who certified that Woe was mentally ill and dangerous to her self never examined her before the hearing, and never spoke to her during it. Woe's lawyer and the judge never advised Woe of her right to appeal or to commit herself voluntarily, the suit claims.

It says Woe, who has been released, fears that her family may try to commit her again.

In Doe's case, the suit claims that she was given a 15-minute hearing last November after an argument with relatives, and was committed to Northern Virginia Mental Health Institute in Falls Church, although she was never examined by a physician and met her court-appointed attorney only minutes before the hearing. She is still confined.

Plotkin, the lawyer who filed the suit, said the project has received an abnormally high number of complaints about commitment hearings in Arlington. "I don't know if that means Arlington is worse than any other place," he said. place," he said.