"Two years after enacting the SRA, Congress passed the Anti-Drug Abuse Act of 1986 (ADAA),48 which incorporated a tiered system of minimum sentences for crack, powder cocaine, and other commonly abused substances based on the quantity of the drugs involved.49 The ADAA was passed in the midst of public paranoia and outcry over the crack epidemic and the fear of AIDS being spread through drug use.50 This political climate led to broad bipartisan support for the ADAA, with the bill passing the House by a 392-16 vote and the Senate on a voice vote.51"

Source

Mascharka, Christopher, "Mandatory Minimum Sentences: Exemplifying the Law of Unintended Consequences," Florida State University Law Review (Tallahassee, FL: Florida State University, Summer 2001) Volume 28, Number 4, p. 941.
http://www.law.fsu.edu/journa…