Minnesota law enforcement would be prohibited from using drones for routine surveillance or to gather evidence against citizens under a bill introduced Thursday.

The measure, sponsored by Sen. Sean Nienow, R-Cambridge, is part of a push this year in state legislatures around the country, reflecting growing concerns about the domestic use of what are technically known as unmanned aerial vehicles. Nienow said his bill is patterned after similar legislation introduced in Indiana.

Describing himself as a supporter of keeping government at bay, Nienow said the legislation would not prohibit law enforcement's use of drones to counter high risk of a terrorist attack, if a warrant is obtained or if there is a reasonable suspicion it needs to act to prevent imminent danger.

But it would keep police from conducting routine surveillance on citizens or groups that might be meeting to demonstrate or protest. Any evidence obtained from using a drone under those circumstances would not be admissible in court.

"If there's a legitimate court order or a legitimate concern of imminent public threat, then go ahead, use the tools you have," he said. "But we shouldn't use it just to go and check stuff out. We shouldn't be flying over people's back yards to see what they are doing."

The U.S. military's use of drones during the Afghanistan and Iraq wars and their continued use by U.S. intelligence agencies in places like Yemen remain the subject of international debate. The domestic use of drones also has raised civil liberties questions as the technology advances and costs of operation come down.

At least 10 states have introduced drone legislation, including California, Texas, Florida, Oregon and North Dakota.

Nienow's bill does not address military use of drones or other domestic uses, such as land surveying or commercial use. The Minnesota National Guard's training site at Camp Ripley, near Little Falls, has become a center for drone training.

Mark Brunswick • 612-673-4434