In November, 2004, Senator Richard Durbin (D-IL) introduced a bill to provide an affirmative defense in federal prosecutions for people who comply with state law in the use of medical marijuana. From the press release by the Marijuana Policy Project:

U.S. Sen. Richard Durbin (D-IL), joined by Sens. Patrick Leahy (D-VT) and Jim Jeffords (I-VT), have introduced the first-ever Senate bill to ensure that federal juries hear the full story when medical marijuana patients and providers, operating legally under state law, are tried on federal marijuana charges.

S. 2989 is similar to H.R. 1717, the "Truth in Trials Act," introduced by a bipartisan House coalition last year and inspired in part by the case of Ed Rosenthal. In January 2003, Rosenthal was found guilty of felony marijuana cultivation charges by a jury that was not allowed to consider that the marijuana was for medical use by seriously ill patients and was grown with the authorization of the city of Oakland, California.