The information about the federal enforcement of the criminal laws by the ATF and the Justice Department on this Web site comes from many sources. This is a guide to the major agency data sources that were used. It is organized by Web site area.

  ATF at Work
This area draws upon a wide scope of information sources, including background information about the agency, its history and evolving responsibilities, as well as its activities. Key sources of information were ATF agency reports, congressional hearings, GAO reports, budget documents, federal court records, and interviews. Prior scholarly work on the agency was also examined. Specific figures reported are drawn from other areas on this site, sources for which are discussed below.

  National Profile and Enforcement Trends Over Time
Data on ATF referrals for criminal prosecution to all levels (federal, state, and local) come from Hearings Before a Subcommittee on the Treasury, Postal Service, and General Government Appropriations of the House Committee on Appropriations, 104th Congress, 1st Session, 1995 [for years 1985-1991] and ATF internal case summaries [for years 1992 onward]. Historical staffing information about the ATF was obtained from the Office of Personnel Management. Data sources on criminal enforcement are discussed at more length below in the section on district enforcement.

  District Enforcement Annual Layers
The primary source for these figures is the federal prosecutor database compiled by TRAC from U.S. Justice Department case management data systems. Coverage includes all referrals recommending criminal prosecution recorded as received by federal prosecutors where the Immigration and Naturalization Service is recorded by Justice as the lead investigative agency. All criminal enforcement figures are based upon number of individuals (defendants or potential defendants) involved -- rather than number of cases. A single referral or case filed in court may involve more than one individual. Each defendant involved is separately counted in these figures.

Population figures used in computing per capita rates and ranks are county level annual estimates from the United States Census Bureau.

ATF staff figures are based upon the number of individuals on the payroll at the end of the fiscal year by post-of-duty and were compiled by TRAC from Office of Personnel Management sources. Unless otherwise noted, the figures include only fulltime staff in each occupational series. Geographic breakdowns (beyond a DC, rest of US breakdown) were not available after fiscal year 1995.