28 CFR Part 35 Nondiscrimination on the Basis of Disability in State and Local Government Services (1991 ADA Title II Regulations)

(2) A public entity shall not discriminate on the basis of illegal use of drugs against an individual who is not engaging in current illegal use of drugs and who--

(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.