>https://www.law.berkeley.edu/library/resources/disasters/Crockett.pdf
Section 333, the primary portion of the Act amended in October 2006, permits the President, without a request from a State, to authorize the armed forces to suppress insurrection, domestic violence, unlawful combination, or conspiracy in a State under certain conditions.
Under the pre-amendment version of the Act, these conditions are twofold.
First, where the insurrection, domestic violence, unlawful combination, or conspiracy hinders the execution of the laws of a State and the laws of the United States to the point where the people are deprived of a right, privilege or immunity, or other named constitutional right, and where the authorities of the State fail, or are unable to protect that right, privilege or immunity, the President may use the military to suppress the insurrection, domestic violence, unlawful combination, or conspiracy.35
Second, where the insurrection, domestic violence, unlawful combination, or conspiracy opposes or obstructs the execution of the laws of the United States, the President may employ the military to suppress it.