Brandon Rittiman

KUSA

DENVER— In a move that could threaten the state's entire legal-marijuana system, a Colorado lawyer claims that requiring pot companies to pay taxes violates the US Constitution.

Attorney Rob Corry is asking the Denver District Court to block marijuana taxes in Colorado, with a lawsuit Colorado's tax system violates the Fifth Amendment, which protects people from self-incrimination.

Corry argues that when marijuana growers and sellers pay their taxes, they effectively incriminate themselves under federal law, which still bans marijuana.

Corry says he's concerned that the taxes on pot are so heavy that they undermine the goal of legalizing the drug in the first place.

"It's pretty clear that the black market never going to go away with these taxes," said Corry, who is seeking a preliminary injunction to block the state from collecting tax on pot as part of his case.

If the injunction is denied, Corry tells 9NEWS he'll advise pot shops to stop paying their taxes, a move that would likely prompt the state to suspend their retail licenses.

Supporters and opponents of the lawsuit agree that the case threatens the entire state-sanctioned marijuana industry, not just the shops Corry represents.

The lawsuit invokes the supremacy clause of the US Constitution, arguing "federal law is supreme over, and preempts, state or local law."

A strict interpretation of that argument could pave the way for Colorado's own court system to find its state system for selling pot illegal.

Corry called that an outside chance, but didn't seem concerned at the possibility.

"In my mind overtaxation is just as bad as prohibition," Corry told 9NEWS.

Other pro-marijuana attorneys tell 9NEWS they are studying the suit, concerned about the wider impact it could have. The state attorney general's office scoffed at the lawsuit.

"Mr. Corry's claims are bizarre and lack legal and logical consistency," said Carolyn Tyler, spokesperson for Attorney General John Suthers. "We will aggressively defend the state against any legal challenge."

Corry, who has had his own legal troubles with marijuana, is used to butting heads with government officials and even other pro-marijuana activists.

He made headlines for handing out free joints as part of his fierce opposition to the 2013 ballot question which enacted state taxes on marijuana, a move critics say resulted in more scrutiny and stricter local regulations of marijuana from the city of Denver.

Opponents of the tax question were upset that lawmakers included a sales tax not originally envisioned by Amendment 64, but Colorado voters approved the amendment by a 2-1 margin.

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