36 CFR Part 1194 Electronic and Information Technology Accessibility Standards (Section 508 Standards)

(b) When procuring a product, each agency shall procure products which comply with the provisions in this part when such products are available in the commercial marketplace or when such products are developed in response to a Government solicitation.  Agencies cannot claim a product as a whole is not commercially available because no product in the marketplace meets all the standards.  If products are commercially available that meet some but not all of the standards, the agency must procure the product that best meets the standards.