Mandatory Minimums vs. Sentencing Guidelines
"Despite their general leveling effect, mandatory minimums can actually increase sentencing disparities in some cases. For example, as the US Sentencing Commission (1991, p. 31) points out, the law provides for large sentencing step-ups or "cliffs" over tiny quantity ranges. A first-time offender found to be in possession of 5.1 grams of crack must be sentenced to at least 5 years in prison. But a first-time offender found to be in possession of 5.0 grams of crack misses the mandatory minimum criterion and can be imprisoned for at most one year. Thus, these two very similar offenders draw sentences differing by at least four years. (Of course, any sentencing regime based at least partly on amounts possessed is likely to include such step-ups. But sentencing guidelines allow for smaller and more numerous steps or ranges that may overlap, and they allow other factors to be considered within those ranges.)"
Caulkins, J., et al., Mandatory Minimum Drug Sentences: Throwing Away the Key or the Taxpayers' Money? (Santa Monica, CA: RAND Corporation, 1997), p. 16.