28 CFR § 35.131 - Illegal use of drugs.
(i) Has successfully completed a supervised drug rehabilitation program or has otherwise been rehabilitated successfully;
(ii) Is participating in a supervised rehabilitation program; or
(iii) Is erroneously regarded as engaging in such use.
(b) Health and drug rehabilitation services.
(1) A public entity shall not deny health services, or services provided in connection with drug rehabilitation, to an individual on the basis of that individual's current illegal use of drugs, if the individual is otherwise entitled to such services.
(c) Drug testing.
(1) This part does not prohibit a public entity from adopting or administering reasonable policies or procedures, including but not limited to drug testing, designed to ensure that an individual who formerly engaged in the illegal use of drugs is not now engaging in current illegal use of drugs.