U.S. District Judge Mary Scriven -- who had previously issued a temporary injunction against enforcing the law -- ruled Tuesday the law violates the constitutional ban on unreasonable searches and seizures, and permanently banned Florida from enforcing the testing, the New York Times reported.
"The court finds there is no set of circumstances under which the warrantless, suspicionless drug testing at issue in this case could be constitutionally applied," Scriven said Tuesday.
In Florida, 4,086 welfare recipients were subjected to drug testing and only 108 tested positive, less than 3 percent. The state spent more money on the testing than it saved by cutting benefits.
Gov. Rick Scott, who made drug testing a campaign issue, promised to appeal.
"Any illegal drug use in a family is harmful and even abusive to a child," he said in a statement. "We should have a zero-tolerance policy for illegal drug use in families -- especially those families who struggle to make ends meet and need welfare assistance to provide for their children."
A similar Michigan law was struck down by a federal court in 2003. The American Civil Liberties Union challenged the 2009 Florida law on behalf of Luis Lebron, a Navy veteran and single father who also cares for his disabled mother.
"The courts are now signaling to politicians that they are not going to treat poor people as if they were exempt from constitutional rights," Howard Simon, executive director of the ACLU of Florida, said.