"Mandatory minimum sentence laws appear to be contributing to increased sentence length, making more emphatic a trend in drug cases that predated their enactment. Mandatory minimum statutes and the guidelines seem also to have narrowed the difference in the sentences imposed for equally serious offenses involving marijuana and opiates, and to have red uced the importance of age and the distinction between leadership and middleman roles in the sentencing decision. In all instances, the narrowing of differences stems from more severe sentencing of the previously advantaged group.
"Mandatory minimum sentence laws do not seem to have ensured that all of those involved in the proscribed behaviors receive at least the minimum term: just under one-half of those who would apparently be eligible received lesser sentences. Further, despite the laws' emphasis on offense behavior, sentences still vary by offender characteristics. As in the past, the least culpable offenders, and offenders who are women, continue to receive less severe sentences than others involved in similar offenses. Further, both black and Hispanic offenders now receive noticeably more severe sentences than their white counterparts.
"The latter trend suggests that there may be questions to be considered concerning the impact of shifting discretion affecting sentencing from the court to the prosecutor's office."

Source

Meierhoefer, B. S., "The General Effect of Mandatory Minimum Prison Terms: A Longitudinal Study of Federal Sentences Imposed" (Washington DC: Federal Judicial Center, 1992), p. 25.
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