Chambliss RELATED VIDEO CNN's Kathleen Koch reports on the illegal use of medical screening Windows Media 28K 56K

From Reporter Kathleen Koch

WASHINGTON (CNN) -- Employers in the United States are increasingly requiring medical tests of both potential and current employees, including drug and alcohol tests.

And while that's perfectly legal under certain circumstances, some critics believe many employers are crossing the line and using test data improperly.

"What we're seeing is employers who are trying to find out people who might be sick in the future, who might run up the company's medical bills, and (efforts) to screen them out, even though the company knows they can do the job perfectly well," says Lewis Maltby of the American Civil Liberties Union.

One case being closely watched is a suit brought against Rockwell International by the Equal Employment Opportunity Commission on behalf of more than 80 workers who applied for jobs at an Illinois plant that produces plastic parts.

Harold Chambliss, 59, was one of them. He says he was given a physical and a test designed to see if he might someday develop carpal tunnel syndrome, a condition caused by repetitive hand movements.

"They told me I didn't pass the carpal tunnel test, which I didn't know what it was, actually. Never heard of it," Chambliss says.

"I felt like I could do probably about any job that they had up there," he said.

Medical testing is legal once a job offer has been made and during the course of a worker's employment, provided that the exam is directly relevant to job requirements.

But the EEOC charges that Rockwell was using testing to screen out people it thought might one day become a burden.

"The decision whether or not to hire someone ... cannot be based on insurance considerations, workers' comp considerations -- any kind of speculation about what might happen to the person in the future," says Peggy Mastroianni of the EEOC.

Rockwell, which no longer owns the plant, denies it did anything improper.

In one recent survey, more than 75 percent of companies said they perform some sort of medical screening, with most of the focus on new hires.

"You can't hire people to do a job who are physically incapable of performing it -- not only today when you hire them but tomorrow and down the road," says Eric Greenberg of the American Management Association. "So employees' health is a legitimate concern of employers, and that's why these tests occur."

The scope of testing may soon become wider. Genetic testing is expected to become more common as the cost of the tests go down and as they are perfected to detect more potential illnesses.