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’s 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 …