In order to ensure that suppliers act in a manner that adheres to a business' own standards, many businesses establish standards of conduct that set expectations for behavior of their suppliers. This is especially important for businesses that rely on suppliers in other countries.
Many businesses include expectations of non-discrimination in their supplier standards.
IBM Suppliers will not discriminate in hiring and employment practices on grounds of race, religion, age, nationality, social or ethnic origin, sexual orientation, gender,gender identity or expression, marital status, pregnancy, political affiliation, or disability.
-- "IBM Supplier Conduct Principles: Guidelines" [PDF]
Sample Contract Language
[BUSINESS] requires that the Supplier shall not discriminate against an employee, volunteer, or participant of the Supplier on the basis of race, color, gender, pregnancy, marital status, familial status, sexual orientation, gender identity or expression, religion, ancestry, national origin, disability, or age except that programs may target services for specific participant groups as defined in the Request for Proposal or Response to the Request for Proposal. Additionally, agencies receiving funds shall demonstrate the standards, policies, and practices necessary to render services in a manner that respects the worth of the individual and protects and preserves the dignity of people of diverse cultures, classes, races, religions, sexual orientations, gender identities or expressions and ethnic backgrounds. It is expressly understood that upon receipt of evidence of discrimination under any of these categories, [BUSINESS] shall have the right to terminate this Agreement. If the Supplier or any owner, subsidiary, or other firm affiliated with or related to the Supplier, is found by the responsible enforcement agency or the courts to be in violation of this agreement or applicable laws, [BUSINESS] will conduct no further business with the Supplier.
-- Sample language courtesy of a large Southern health system
Such standards should require a supplier to prove or otherwise verify that it does in fact adhere to the non-discrimination standards.