The number of defendants prosecuted in U.S. district courts increased at an average annual rate of 3.9% between 1980 and 1993. Between 1993 and 1995, Federal prosecutions decreased by 12.6% before increasing to the level attained during 1993.

Convictions and imprisonments followed the same general pattern. As a proportion of convictions, imprisonments increased from 46% during 1980 to 71% during 1999.