41 U.S.C. § 3303: Exclusion of particular source or restriction of solicitation to small business concerns

increase or maintain competition and likely result in reduced overall cost for the procurement, or for an anticipated procurement, of the property or services; be in the interest of national defense in having a facility (or a producer, manufacturer, or other supplier) available for furnishing the property or service in case of a national emergency or industrial mobilization; be in the interest of national defense in establishing or maintaining an essential engineering, research, or development capability to be provided by an educational or other nonprofit institution or a Federally funded research and development center; ensure the continuous availability of a reliable source of supply of the property or service; satisfy projected needs for the property or service determined on the basis of a history of high demand for the property or service; or satisfy a critical need for medical, safety, or emergency supplies. A determination under paragraph (1) may not be made for a class of purchases or contracts. An executive agency may provide for the procurement of property or services covered by section 3301 of this title using competitive procedures, but excluding other than small business concerns in furtherance of sections 9 and 15 of the Small Business Act ( 15 U.S.C. 638 , 644). A contract awarded pursuant to the competitive procedures referred to in subsections (a) and (b) is not subject to the justification and approval required by section 3304(e)(1) of this title .