The Robert T. Stafford Disaster Relief and Emergency Assistance Act of 1988, (42 U.S. Code 5191) is the principal legal authority for U.S. Federal responses to domestic disasters. Its full invocation requires a Presidential proclamation of a disaster, which then authorizes the Federal Emergency Management Agency (FEMA) and the U.S. Department of Homeland Security to respond. 
One of the key attributes of invoking the Act is that FEMA can draw on a preestablished disaster assistance fund, without waiting for explicit Congressional legislation.
- Title 42 (Public Health and Welfare), Chapter 68 (Disaster Relief), Subchapter IV-A (Emergency Assistance Programs), Section 5191. Procedure for declaration
- Keith Bea (29 August 2005), Federal Stafford Act Disaster Assistance: Presidential Declarations, Eligible Activities, and Funding, Congressional Research Service