"The precise terms of the legislation that would address the discrepancy were somewhat more difficult to devise. Eventually, however, it was agreed that (1) the threshold quantity of crack necessary to implicate the five-year mandatory minimum would be increased to twenty-eight grams, or approximately one ounce (effectively creating an 18:1 powder-to-crack ratio);142 (2) a similar upward adjustment would be made to the quantity of crack necessary for a defendant to receive a ten-year minimum term;143 (3) the five-year mandatory minimum sentence applicable to mere possession of crack would be abolished;144 and (4) more severe penalties would apply to drug crimes involving violence, threats of violence, or other aggravating circumstances.145 Retention of some disparity between crack and powder cocaine was essential to pas-sage of the Act, because many members of Congress continued to believe (with some justification)146 that given its customary methods of distribution and administration, crack was at least somewhat more powerful, more addictive, and more closely tied to violent crime than powder cocaine was.147 To these Senators and Representatives, these differences supported some distinction be-tween powder and crack cocaine—just not a 100:1 discrepancy.148 By adopting an 18:1 ratio, instead of equalizing the penalties attached to crack and powder cocaine, the measure that would be-come the Fair Sentencing Act assuaged these concerns and facilitated its enactment into law."

Source

Graham, Kyle, "Sorry seems to be the hardest word: The Fair Sentencing Act of 2010, Crack, and Methamphetamine, "University of Richmond Law Review (Richmond, VA: Richmond School of Law, March 2011) Vol. 45, Issue 3, pp. 792-793.
http://lawreview.richmond.edu…