Since 2010 the FBI quietly has been screening applicants on behalf of Colorado officials in an attempt to weed out -- pun intended -- narcos and other undesirables from operating pot shops as reported by Gene Johnson for The Associated Press.
It's one thing for the FBI to turn a blind eye to the pot shops which are legal under state law but remain illegal under federal law; however, it's quite another thing for the once-storied agency to enable these drug ventures by conducting the background checks on wouldbe sellers in the licensing process.
Meanwhile, even as the FBI is clearing folks to run pot shops and grow operations in Colorado, the DEA apparently is concerned that some of them nevertheless may have ties to Colombian cartels as reported by Jeremy Jojola for KUSA: "the sources close to the investigation say federal agents are gathering evidence that will show profits made from several cannabis grow operations are flowing back to Colombia."
Query whether federal prosecutors now are precluded from targeting any marijuana traffickers since the Justice Department is giving a pass to the pot shops which are in compliance with state law but otherwise in flagrant violation of federal law. The Equal Protection Clause under the 14th Amendment prohibits selective enforcement of the federal drug laws, and the DOJ will be hard pressed to prosecute a pot dealer in one state when it lets a pot shop in another state get away with the same crime.
Further reading that may be of interest: