DULUTH, Minn. — A Duluth head shop was devoid of customers as a city ordinance regulating synthetic drugs kicked in.

Potential buyers at the Last Place on Earth were greeted Thursday with a sign on the door saying the shop wasn't selling any so-called "incense" products. Callers to the store were told that the ban was temporary and that they might have products available by early next week.

Owner Jim Carlson tells the Duluth News Tribune (http://bit.ly/1awahvv ) he's awaiting a court decision that he hopes will allow him to sell synthetics despite the city ordinance requiring him to have a license. A federal magistrate judge has scheduled a hearing on his motion Friday.

Carlson's attorney, Randall Tigue, says the city's new requirement that retailers get a license to sell synthetic drugs is unconstitutional.