29 CFR § 1630.6 - Contractual or other arrangements.
(a) In general. It is unlawful for a covered entity to participate in a contractual or other arrangement or relationship that has the effect of subjecting the covered entity's own qualified applicant or employee with a disability to the discrimination prohibited by this part.
(b) Contractual or other arrangement defined. The phrase contractual or other arrangement or relationship includes, but is not limited to, a relationship with an employment or referral agency; labor union, including collective bargaining agreements; an organization providing fringe benefits to an employee of the covered entity; or an organization providing training and apprenticeship programs.
(c) Application. This section applies to a covered entity, with respect to its own applicants or employees, whether the entity offered the contract or initiated the relationship, or whether the entity accepted the contract or acceded to the relationship. A covered entity is not liable for the actions of the other party or parties to the contract which only affect that other party's employees or applicants.