From the Summary: "Enacted in 1966 after 11 years of investigation, legislative development, and deliberation in the House and half as many years of such consideration in the Senate, the Freedom of Information Act (FOIA) displaced the ineffective public information section of the Administrative Procedure Act. The FOIA was designed to enable any person -- individual or corporate, regardless of citizenship -- to request, without explanation or justification, presumptive access to existing, identifiable, unpublished, executive branch agency records on any topic. The statute specified nine categories of information that may be permissibly exempted from the rule of disclosure. Disputes over the accessibility of requested records could be ultimately settled in court."
CRS Report for Congress, RL32780