It is the largest federal government reorganization since the Department of Defense was created via the National Security Act of 1947 (as amended in 1949).

These reflect compromises with other committees needed to secure passage, but the result is at times inconsistent or conflicting authorities.

For example, the Act identifies the Department of Homeland Security's (DHS) first responsibility as preventing terrorist attacks in the United States; but, the law's language makes clear that investigation and prosecution of terrorism remains with the Federal Bureau of Investigation and assigns DHS only an analytical and advisory role in intelligence activities.

[7] Similarly, with Critical Infrastructure Protection (CIP), which relates to the preparedness and response to serious incidents, the Act gave DHS broad responsibility to minimize damage but only limited authority to share information and to coordinate the development of private sector best practices.

[9] Title V and Title II outline the way the department ensures that the use of intelligence and its own threat analysis of terrorist capabilities are intended to distribute funds to those areas where the terrorist threat is greatest, and that states provide the Federal Government with their Emergency Response Plans so that the department can coordinate priorities regionally and nationally.