Entities Subject to FOIA

Introduction
FOIA applies to most "agencies" within the executive branch of the federal government. It does not apply to Congress, the courts, or state or local entities.

Statutory definition
"Agency", as defined in 5 U.S.C. 552(f)(1), includes

"any executive department, military department, Government corporation, Government controlled corporation, or other establishment in the executive branch of the Government (including the Executive Office of the President), or any independent regulatory agency;"

The President
In Kissinger, the U.S. Supreme Court held that the meaning of “agency” under FOIA does not include “the President's immediate personal staff or units in the Executive Office [of the President] whose sole function is to advise and assist the President.”