OncorMed has also advertised to doctors outside the network that it can now test patients for cancer genes.

Asked whether hospitals should routinely test patients for AIDS upon admission, Dr. Koop said the real problem was with surgical patients.

Here, in America, we tested patients on Shutter Island.

As a result, they decided he would test patients and refuse to operate on anyone who was a carrier of the AIDS virus.

When Dr. Damasio tested other patients with similar brain damage he found the same striking combination of impaired reason and impaired affect.

Dr. Marc Ladenheim, a cardiologist in Burbank, Calif., who has tested patients for several years, said more severe disease correlated with greater rates of aspirin resistance.

"A law requiring doctor testing without allowing us to test patients would cause a severe backlash," Dr. Gottesman said.

(These reactions are now rare since doctors began testing patients for allergic reactions by using a simple skin test.)

The U.S. military also tested unsuspecting patients, exposing citizens to germ warfare agents and LSD in the '50s and '60s.

In approving a resolution to make it easier to test patients, the association plans to create new consent forms to be used in hospitals and clinics that want to test for the virus.