SEATTLE -- The FBI is refusing to run nationwide background checks on people applying to run legal marijuana businesses in Washington state, even though it has conducted similar checks in Colorado -- a discrepancy that illustrates the quandary the Justice Department faces as it allows the states to experiment with regulating a drug that's long been illegal under federal law.

Washington state has been asking for nearly a year if the FBI would conduct background checks on its applicants, to no avail. The bureau's refusal raises the possibility that people with troublesome criminal histories could wind up with pot licenses in the state -- undermining the department's own priorities in ensuring that states keep a tight rein on the nascent industry.

It's a strange jam for the feds, who announced last summer that they wouldn't sue to prevent Washington and Colorado from regulating marijuana after 75 years of prohibition.

The Obama administration has said it wants the states to make sure pot revenue doesn't go to organized crime and that state marijuana industries don't become a cover for the trafficking of other illegal drugs. At the same time, it might be tough for the FBI to stomach conducting such background checks -- essentially helping the states violate federal law.

The Justice Department declined to explain why it isn't conducting the checks in Washington when it has in Colorado. Stephen Fischer, a spokesman for the FBI's Criminal Justice Information Services Division, referred an Associated Press inquiry to DOJ headquarters, which would only issue a written statement.

"To ensure a consistent national approach, the department has been reviewing its background check policies, and we hope to have guidance for states in the near term," it said in its entirety.

In Washington, three people so far have received licenses to grow marijuana -- without going through a national background check, even though the state Liquor Control Board's rules require that they do so before a license is issued.

"The federal government has not stated why it has not yet agreed to conduct national background checks on our behalf," Washington state Liquor Control Board spokesman Brian Smith said in an email. "However, the Liquor Control Board is ready to deliver fingerprints as soon as DOJ is ready."

In the meantime, officials are relying on background checks by the Washington State Patrol to catch any in-state arrests or convictions. Applicants must have lived in Washington state for three months before applying, and many are longtime Washington residents whose criminal history would likely turn up on a State Patrol check. But others specifically moved to the state in hopes of joining the new industry.

"Both Washington state and Washington, D.C., have been unequivocal that they want organized crime out of the marijuana business," said Alison Holcomb, the Seattle lawyer who authored the legal pot law.