Alcoholism, and use of illicit drugs is not covered under the ADA. Anyone who is currently using drugs illegally is not protected by the ADA and may be denied employment or fired on the basis of such use.
The ADA does not prevent employers from testing applicants or employees for current illegal drug use, nor from making employment decisions based on testing results that are verifiable. A test for the illegal use of drugs is not considered a medical examination under the ADA. Therefore, it is not a prohibited pre-employment medical examination and you will not have to show that the administration of the test is job-related and consistent with business necessity. The ADA does not encourage, authorize or prohibit drug tests.
A worker who is an alcoholic is a person with a disability and is protected by the ADA if he or she is qualified to perform the essential functions of the job. However, the ADA still allows employers to discipline, discharge or deny employment to an alcoholic whose use of alcohol negatively affects job performance or conduct. An employer also may ban the use of alcohol in the workplace and can require that employees not be under the influence of alcohol, as long as that rule is uniformly applied.
There may be times, however, when an employer must accommodate an employee with alcoholism. For example, an employer may have to modify a rule prohibiting personal phone calls at work for an employee with alcoholism who periodically has to contact his AA sponsor, if the employee has a need to do so during work hours.