In 1999, the State of Michigan implemented a plan to drug test applicants for public assistance. The ACLU, with the assistance of Drug Policy Alliance, challenged this policy in federal court in the case Marchwinski v. Michigan. For the case, the Alliance conducted a nationwide survey of state drug testing policies with respect to public benefits, revealing that the other 49 states used alternative, far less intrusive methods to detect drug abuse among welfare applicants and recipients. The Alliance study was introduced as evidence in the ACLU brief and was cited by the United States District Court in its decision to strike down Michigan's drug testing policy as unconstitutional.

The State of Michigan appealed to the Court of Appeals for the Sixth Circuit. In the Court of Appeals, Drug Policy Alliance filed an amicus brief on behalf of the American Public Health Association and several other organizations opposing Michigan's policy of drug testing applicants for public assistance, arguing that there are far less intrusive and more accurate methods for detecting drug abuse, that suspicionless drug testing is contrary to the goals of self-sufficiency and employability central to the Personal Responsibility and Work Opportunity Act, and that the drug testing erodes the trust relationship between a recipient and social worker. This relationship is essential in helping a recipient achieve the goal of self-sufficiency and independence from the welfare system.

In a decision on October 2002, a three-judge panel of the Sixth Circuit held that Michigan's policy did not violate the Fourth Amendment rights of welfare applicants. However, the full Sixth Circuit granted a motion to rehear the case en banc. The Court then asked Drug Policy Alliance to resubmit its amicus brief to the full Court.

A new hearing was held in March 2003. In April 2003, the 12-member en banc panel of the 6th Circuit Court of Appeals overturned the October ruling of the three judge panel and reinstituted the original District Court decision striking down Michigan’s drug testing plan.