29 CFR Part 1630, Regulations to Implement the Equal Employment Provisions of the ADA (Title I Regulations with amendments issued through May 2016)

(b) Charges of discriminatory application of selection criteria—

(1) In general. It may be a defense to a charge of discrimination, as described in §1630.10, that an alleged application of qualification standards, tests, or selection criteria that screens out or tends to screen out or otherwise denies a job or benefit to an individual with a disability has been shown to be job-related and consistent with business necessity, and such performance cannot be accomplished with reasonable accommodation, as required in this part.

(2) Direct threat as a qualification standard. The term “qualification standard” may include a requirement that an individual shall not pose a direct threat to the health or safety of the individual or others in the workplace. (See §1630.2(r) defining direct threat.)