Pardon the hijack; here’s more on federalizing the National Guard (President Kennedy cited both sections in his executive order, and they remain part of the U.S. Code). Again, I have no reason to think either section will be invoked any time soon, if ever:
*U.S. Code, Title 10, Chapt. 15, §332. Use of militia and armed forces to enforce Federal authority.
*
Whenever the President considers that unlawful obstructions, combinations, or assemblages, or rebellion against the authority of the United States, make it impracticable to enforce the laws of the United States in any State by the ordinary course of judicial proceedings, he may call into Federal service such of the militia of any State, and use such of the armed forces, as he considers necessary to enforce those laws or to suppress the rebellion.
§ 333. Major public emergencies; interference with State and Federal law.
(a) Use of Armed Forces in Major Public Emergencies.
(1) The President may employ the armed forces, including the National Guard in Federal service, to-
(A) restore public order and enforce the laws of the United States when, as a result of a natural disaster, epidemic, or other serious public health emergency, terrorist attack or incident, or other condition in any State or possession of the United States, the President determines that—
(i) domestic violence has occurred to such an extent that the constituted authorities of the State or possession are incapable of maintaining public order; and
(ii) such violence results in a condition described in paragraph (2); or
(B) suppress, in a State, any insurrection, domestic violence, unlawful combination, or conspiracy if such insurrection, violation, combination, or conspiracy results in a condition described in paragraph (2).
(2) A condition described in this paragraph is a condition that—
(A) so hinders the execution of the laws of a State or possession, as applicable, and of the United States within that State or possession, that any part or class of its people is deprived of a right, privilege, immunity, or protection named in the Constitution and secured by law, and the constituted authorities of that State or possession are unable, fail, or refuse to protect that right, privilege, or immunity, or to give that protection; or
(B) opposes or obstructs the execution of the laws of the United States or impedes the course of justice under those laws.
(3) In any situation covered by paragraph (1)(B), the State shall be considered to have denied the equal protection of the laws secured by the Constitution.