WASHINGTON (AP)—The Supreme Court strengthened workers’ protection against sexual harassment Tuesday, ruling unanimously that employers can be forced to pay monetary damages even when employees suffer no psychological harm.

‘‘So long as the environment would reasonably be perceived, and is perceived, as hostile or abusive, there is no need for it also to be psychologically injurious,’‘ Justice Sandra Day O’Connor wrote as the court revived a Tennessee woman’s lawsuit against her ex-boss.

The woman said her boss, among other things, had asked her to retrieve coins from his front pants pocket, suggested they go to a local motel to negotiate her pay raise and asked if she gained a sales contract by providing sexual favors.

‘‘It’s a big win for women,’‘ Marcia Greenberger of the National Women’s Law Center said of the ruling. ‘‘I don’t think the court could have sent a clearer signal that employers have to take sexual harassment in the workplace seriously.’‘

The 9-0 vote emphasizes that ‘‘sexual harassment is just as much a violation of the law as other forms of discrimination,’‘ Greenberger said.

The decision comes at a time when complaints over alleged sexual harassment in employment are increasing.

The Equal Employment Opportunity Commission says such complaints rose 53 percent in the year following Anita Hill’s accusations during Justice Clarence Thomas’ 1991 confirmation hearing.

Hill said Thomas had harassed her years earlier, but Thomas strongly denied any such conduct.

He sat silently during courtroom arguments in the Tennessee case last month, and he offered no separate written opinion Tuesday.

The high court ruled in 1986 that on-the-job sexual harassment is illegal—a violation of the anti-bias law known as Title VII of the Civil Rights Act of 1964—if it is ‘‘sufficiently severe or pervasive to alter the conditions of the victim’s employment.’‘

That ruling banned ‘‘hostile’‘ or ‘‘abusive’‘ workplace environments caused by various discriminatory motives.

Tuesday’s decision reaffirmed, and clarified somewhat, the 1986 ruling.

‘‘When the workplace is permeated with discriminatory intimidation, ridicule and insult that is sufficiently severe or pervasive to alter the conditions of the victim’s employment and create an abusive working environment, Title VII is violated,’‘ O’Connor said.

She acknowledged that the ruling offers no ‘‘mathematically precise test.’‘

‘‘Whether an environment is ‘hostile’ or ‘abusive’ can be determined only by looking at all the circumstances,‘’ she said. ‘‘These may include the frequency of the discriminatory conduct; its severity; whether it is physically threatening or humiliating, or a mere offensive utterance, and whether it unreasonably interferes with an employee’s work performance.’‘

Teresa Harris sued her ex-boss, Charles Hardy, after resigning in 1987 from her job as a manager at Forklift Systems in Nashville.

Tuesday’s ruling sends Harris’ lawsuit back to the 6th U.S. Circuit Court of Appeals, which had ruled that she could not sue Hardy because she couldn’t prove psychological harm. The appeals court now must decide whether a trial on her allegations is needed.