Backers say the opinion is likely to add legitimacy to the state's budding but unruly medicinal pot dispensary industry, The Denver Post reported Tuesday.
Suthers, a Republican, offered the opinion in a letter written in response to a query from Democratic Gov. Bill Ritter. In the letter, Suthers wrote, "Medical marijuana is tangible property that is generally subject to state sales tax," the newspaper said.
Suthers also reportedly said in the opinion that medical-marijuana dispensaries must obtain retail sales licenses from the state to conduct business.
A spokesman for Ritter indicated the state will immediately begin directing medical marijuana dispensaries to start paying sales tax and obtaining retail licenses.
"Colorado voters have said they want medical marijuana in Colorado," spokesman Evan Dreyer told the Post. "But what we have now is chaos."