Mandatory minimums proliferated during the 1980s-90s "tough on crime" era, especially for drug offenses. Examples include the 1986 Anti-Drug Abuse Act's 5/10-year minimums for crack and powder cocaine.
Recent reform: The First Step Act (2018) reduced some federal mandatory minimums and expanded "safety valve" exceptions. The Fair Sentencing Act (2010) reduced the crack/powder disparity from 100:1 to 18:1.
Defenders argue mandatory minimums ensure proportionate punishment, deter serious crime, and prevent inconsistent sentencing. Critics argue they drive mass incarceration, transfer power from judges to prosecutors, and impose injustice in individual cases.