Most major corporations use health risk assessments in their wellness programs. These questionnaires, which ask employees for information ranging from their health habits to medical conditions and weight, are often part of an overall strategy to help individuals manage their own health or steer them to the best treatment. Many companies use them in their efforts to pinpoint employees likely to benefit from particular programs–helping smokers to quit, for example, or diabetics to eat the right foods.

The trouble is, companies that aren't careful about how they use these assessments run the risk of violating a number of federal laws. "You have to be very aware of the regulatory environment you're working in," says Michael Thompson, a partner at PricewaterhouseCoopers. "And you need to make sure you don't step over the line."

Most important are the following hazards: