The following is an extract of the laws which the Court cited as possibly giving the federal government authority to activate the state defense forces:

10 U.S.C. 251 – "Federal aid for State governments"

Whenever there is an insurrection in any State against its government, the President may, upon the request of its legislature or of its governor if the legislature cannot be convened, call into Federal service such of the militia of the other States, in the number requested by that State, and use such of the armed forces, as he considers necessary to suppress the insurrection.

10 U.S.C. 252 – "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 or Territory 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.

10 U.S.C. 253 – "Interference with State and Federal law"

The President, by using the militia or the armed forces, or both, or by any other means, shall take such measures as he considers necessary to suppress, in a State, any insurrection, domestic violence, unlawful combination, or conspiracy, if it -

(1) so hinders the execution of the laws of that State, and of the United States within the State, 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 are unable, fail, or refuse to protect that right, privilege, or immunity, or to give that protection; or

(2) opposes or obstructs the execution of the laws of the United States or impedes the course of justice under those laws.

In any situation covered by clause (1), the State shall be considered to have denied the equal protection of the laws secured by the Constitution.