The Minnesota Court of Appeals on Monday ruled it unconstitutional for law enforcement to install a GPS tracking device on a vehicle without a warrant, a decision applauded by privacy-rights groups.

The decision followed a 5-year investigation by the Minnesota Department of Natural Resources that resulted in one of the highest-profile poaching cases in the state in recent years.

In January, Lac qui Parle prosecutors charged Joshua Dwight Liebl, 39, with 13 counts related to poaching after a DNR officer obtained a judge's order to secretly install a tracking device on Liebl's truck.

As a result of that tracking, officers confiscated 37 dead deer, 37 guns, an intact piebald white-tailed fawn and other wildlife.

But a district judge ruled in April that the evidence was obtained illegally because the DNR should have obtained a warrant to track Liebl.

The original judge's tracking order required only a suspicion that Liebl was involved in poaching. A warrant requires probable cause. The charges against Liebl were thrown out.

In Monday's ruling, the court of appeals agreed with the district court. "Because the tracking order was not based on a probable-cause finding by the issuing court, the tracking order was not a valid substitute for a search warrant," Appeals Court Judge John Smith wrote.

Lt. Col. Greg Salo of the DNR's enforcement division said it's too early to say whether the agency will petition the Minnesota Supreme Court to hear the case. He said the agency now will seek warrants to install GPS monitors on vehicles.

"There's no doubt [Liebl] was a poacher and violated dozens of game and fish laws," Salo said. "Where we go with this guy, it's hard to say. He's definitely caught our attention now."

Teresa Nelson, legal director for the American Civil Liberties Union of Minnesota, said, "What this means going forward is that it will provide guidance to law enforcement officers around the state to get a traditional warrant as opposed to the shortcut."

Brandon Stahl