No. Individuals who currently engage in the illegal use of drugs are specifically excluded from the definition of an individual with a disability protected by the ADA when the employer takes action on the basis of their illegal drug use.
I’ll give you the “lawyer answer” – it depends. All people who meet the ADA definition of disability are covered by the ADA in general, but they still may not have rights under particular sections of the ADA. For example, there is a section of the ADA that deals only with employment discrimination. If a person with a disability is not employed and is not seeking employment, then that person would not necessarily be covered by that part of the ADA, although the person would be covered by other parts of the ADA.
They may be. While a current illegal user of drugs is not protected by the ADA if an employer acts on the basis of such use, a person who currently uses alcohol is not automatically denied protection. Alcoholism is an impairment, and if it substantially limits a major life activity (e.g., learning, concentrating, interacting with others, caring for oneself) it will constitute a disability. An alcoholic may be person with a disability and protected by the ADA if s/he is qualified to perform the essential functions of the job. An employer may be required to provide an accommodation to an alcoholic, (e.g. a flexible schedule to enable the employee to attend counseling appointments).
However, an employer can discipline, discharge or deny employment to an alcoholic whose use of alcohol adversely affects job performance or conduct. An employer also may prohibit the use of alcohol in the workplace and can require that employees not be under the influence of alcohol.