Workplace violence is increasing, and it demands careful attention, especially in light of the rights afforded employees by the Americans with Disabilities Act (ADA). We asked Joan Ackerstein, a lawyer with Jackson, Lewis, Schnitzler & Krupman in Boston, for some guidelines:

What legal responsibility does a company have to screen out hires who may turn violent?
If an employee gets violent, the company may be sued for negligent hiring and negligent retention. "The former says you should have known before you hired the worker that there was a problem," Ackerstein explains. "The latter says there were clues along the way." The employer's responsibility varies with the job. For instance, if you're managing an apartment complex and you're giving a superintendent keys to people's homes, your responsibility is considerable. Smart companies prepare by conducting thorough background checks, which may extend to personality profiles and criminal-history checks.

What part does the ADA play in this?
The ADA protects the physically and mentally disabled from discrimination. However, it doesn't protect a disability if it presents an immediate threat of substantial harm. A spoken threat from an agitated employee is unlikely to fit that definition. "But if John goes after Henry with a knife," says Ackerstein, "my guess is, that counts."

How do you deal with a person you think may be dangerous?
If someone is simply distracted -- if a worker has broken up with a girlfriend, say -- that's a performance issue. But let's say a worker is not bathing and not changing clothes. That could be a symptom of a serious problem. Ackerstein says, "You can't treat that just as a performance problem, first, because it's not humane, and second, because you might be charged with discrimination under the ADA. The employee may decide you should have recognized their problem."

You might require a note from the worker's physician saying that he or she can work, if you're beginning to have doubts about that. And you might offer a compromise -- time off, perhaps, or shorter hours.

Can you make an employee's job conditional upon getting help?
Though the ADA doesn't specify that, it may qualify as a reasonable accommodation. "You continue to work for us, and you get treatment."

What else can managers do?
"Know whom to call before someone shows up with a gun," Ackerstein says. Form a team to deal with an incident of workplace violence. Decide who will call the police or an ambulance and what exits to seal. In general, be supersensitive to security. "Should guests sign in? Don't allow people to work at night alone. Improve lighting in parking lots," Ackerstein advises.