Using these government data sources, TRAC identified 30,936 defendants who the investigative agencies had targeted for alleged environmental violations during the Clinton-Bush years, including over 20,000 who were actually criminally prosecuted.

Records used cover all federal criminal charges, not merely those cases where an environmental charge appeared as the lead charge. All referrals for prosecution from investigative agencies that were acted upon in any manner in each of the 94 U.S. Attorney offices are covered. Where prosecution resulted, the actual charges brought and any resulting convictions and sentences are recorded. When the assistant U.S. attorney assigned the referral decided not to prosecute, the reasons recorded for declining are included.

With these data it is possible to determine how many of the total eventually were formally charged, convicted and sentenced to prison. While suspected violations under more than 1,400 different federal statutes were covered, most of the charges were recommended under a much smaller number of laws that naturally fall into categories such as wildlife protection, pollution violations, and preservation of our national parks and forests.

To document the shifting enforcement priorities, the number of defendants subject in various ways to environmental charges were divided into three four-year segments, the first term of President Bill Clinton (FY 1993-1996), the second Clinton term (FY 1997-2000) and the current term of President George W. Bush (FY 2001-2004). The database covers all recorded activity through the first quarter of FY 2004.

Because FY 2004 has not ended, estimates for the last three quarters of FY 2004 had to be made in order to allow comparisons for comparable four-year time periods for each administration. Estmates were derived using a projection method which assumed that the level of activity observed during FY 2003 and the first quarter of FY 2004 continued unabated. (The number of actions during each of the four quarters of FY 2003 plus the first quarter of FY 2004 were averaged, and these activity rates were assumed to carry through to the end of FY 2004.) Where trends were downward during the Bush years, this methodology assumes that any decline stopped and trends leveled out during FY 2004. This method thus results in a conservative estimate for any enforcement declines.

Terms Used: Figures for referrals count defendants referred by federal, state and local investigative agencies for criminal prosecution on which some action -- a decision to prosecute or not to prosecute -- by a federal prosecutor has taken place. The recorded date of this action constitutes the referral year. Figures for prosecutions count defendants criminally charged by an indictment, information, complaint or citation being filed. Figures for convictions count defendants convicted in federal court, while figures for prison reflect the numbers out of those convicted who received a prison sentence. The recorded year the prosecution was filed, or the defendant was convicted and sentenced become the prosecution year and the conviction year, respectively.

Sources of data for TRAC's environmental database include central files of the Executive Office for United States Attorney (EOUSA) used for internal management and reports to Congress, as well as data files obtained from each of the 94 U.S. Attorney offices from databases each office maintains to record the case-by-case, defendant-by-defendant activity of each assistant U.S. attorney.

TRAC uses these underlying files as one of several authoritative sources for its public web site, http://trac.syr.edu, and a more sophisticated subscription site, http://tracfed.syr.edu .