42 U.S.C. § 18311

1. (a)
   1. (1)The Federal Government may not acquire human space flight transportation services from a foreign entity unless—
      1. (A)no United States Government-operated human space flight capability is available;
      2. (B)no United States commercial provider is available; and
      3. (C)it is a qualified foreign entity.
   2. (2)In this subsection:
      1. (A)The term “commercial provider” means any person providing human space flight transportation services, primary control of which is held by persons other than the Federal Government, a State or local government, or a foreign government.
      2. (B)The term “qualified foreign entity” means a foreign entity that is in compliance with all applicable safety standards and is not prohibited from providing space transportation services under other law.
      3. (C)The term “United States commercial provider” means a commercial provider, organized under the laws of the United States or of a State, that is more than 50 percent owned by United States nationals.
   3. (3)Nothing in this subsection shall prevent the Administrator from negotiating or entering into human space flight transportation arrangements with foreign entities to ensure safety of flight and continued ISS operations.
2. (b)Congress reaffirms the policy stated in section 70501(a) of title 51, that the United States shall maintain an uninterrupted capability for human space flight and operations in low-Earth orbit, and beyond, as an essential instrument of national security and of the capacity to ensure continued United States participation and leadership in the exploration and utilization of space.