14 CFR Part 382 Nondiscrimination on the Basis of Disability in Air Travel (Air Carrier Access Act) (with amendments issued through May 2016)

(c) You may refuse to provide transportation to any passenger on the basis of safety, as provided in 49 U.S.C. 44902 or 14 CFR 121.533, or to any passenger whose carriage would violate FAA or TSA requirements or applicable requirements of a foreign government.

(1) You can determine that there is a disability-related safety basis for refusing to provide transportation to a passenger with a disability if you are able to demonstrate that the passenger poses a direct threat (see definition in §382.3). In determining whether an individual poses a direct threat, you must make an individualized assessment, based on reasonable judgment that relies on current medical knowledge or on the best available objective evidence, to ascertain:

(i) The nature, duration, and severity of the risk;

(ii) The probability that the potential harm to the health and safety of others will actually occur; and

(iii) Whether reasonable modifications of policies, practices, or procedures will mitigate the risk.

(2) If you determine that the passenger does pose a direct threat, you must select the least restrictive response from the point of view of the passenger, consistent with protecting the health and safety of others. For example, you must not refuse transportation to the passenger if you can protect the health and safety of others by means short of a refusal.

(3) In exercising this authority, you must not act inconsistently with the provisions of this part.

(4) If your actions are inconsistent with any of the provisions of this part, you are subject to enforcement action under Subpart K of this part.