Lawyers from Davis Wright Tremaine have sued the federal government for policy documents that could shed light on why international cannabis workers and investors are being denied entry — sometimes permanently — at the U.S. border.

In a complaint filed Wednesday in the U.S. District Court for Western District of Washington, Davis Wright partner John McKay, a former U.S. attorney in Seattle, and associate Chris Morley said the U.S. Customs and Border Protection has not responded to a request for records about the “policy or practice of denying foreign nationals entry to the U.S. due to their involvement with cannabis businesses in the U.S. and abroad.”

Davis Wright is the sole plaintiff in the Freedom of Information Act lawsuit, although the attorneys acknowledge that the firm represents state-licensed medical and recreational cannabis operators.

“CBP's refusal to produce documents responsive to the FOIA requests has hampered the firm's ability to participate as an informed citizen and to adequately represent its clients,” they wrote.

A representative for the agency said only that “the U.S. Customs and Border Protection does not comment on pending litigation.”

Although Canada and some states have legalized recreational-marijuana markets, the U.S. continues to classify cannabis as a banned narcotic and industry employees, even in areas where marijuana is legal, as drug traffickers.

That's created big potential problems at the border, especially the U.S.-Canadian border, for international investors and industry professionals heading to legalized states for business reasons. Would-be entrants the CBP deems to be lying about their marijuana use or industry ties can be barred from the U.S. for life.

The problem is made worse by seemingly different enforcement practices at different U.S. ports of entry, attorneys say.

“CBP has created a lot of confusion and uncertainty at the border,” Morley said Thursday. “Our clients are entitled to know how this policy is being enforced.”

Davis Wright has asked the customs agency for documents explaining how its agents decide to bar “foreign nationals or aliens who are employed by or invest in foreign cannabis businesses which operate in full compliance with local domestic law of the jurisdiction in which they operate.”

The firm petitioned the court to order the customs and border agency to immediately produce those records and to pay the firm's costs and attorney fees.