"I don't see a federal role," he said in a "Washington Unplugged" interview, noting that his state is among those that allow medical marijuana use. (There is also a push in Colorado for full legalization.) "I don't think that the federal side should be coming in and second guessing what states are doing."
"Just as the policy of prohibition failed nationally with alcohol - it's now up to states and counties - I think we should do the same with marijuana," he said.
Polis said his state's marijuana regulatory structure has been a model for other states, pointing to monitoring of production and dispensaries as well as background checks.He also said he doesn't see "much downside" in moving toward decriminalization or legalization.
"One of the major issues we have with marijuana is its accessibility to minors and underage children, and that's because the corner drug dealer doesn't care if they're selling it to somebody who's 14 years old," he said. "If we regulate it, just like we do with alcohol and tobacco, we can have a real system in place to make sure that minors, young people don't get a hold of substances they shouldn't be using."
Polis is working on legislation to make it easier for growers and distributors to have access to banking services.
"Many banks don't want to take on the perceived risk of dealing with companies that might be in violation of federal law, so we're trying to clarify that if companies are following state law there won't be any risks for asset forfeiture or other risks for the banks," he said.
Polis said it's apparent that "we are not winning the drug war," pointing to increased drug abuse and the flow of drugs across the southern border from criminal cartels."Drug abuse is fundamentally a medical issue, a health issue, more than a criminal issue," he said.
The lawmaker asked people to ask themselves how they would want someone close to them to be treated if they were struggling with drug abuse.
"Do you think that person would have been better served by being in jail for several years or getting the help they needed to end their chemical dependency?" he asked.
Polis also pointed to a recent study finding that marijuana is already a $1.7 billion industry.
"It's already created thousands of jobs in Colorado, several millions dollars of tax revenue - I really think that's just the tip of the iceberg with regard to the potential of the industry in terms of job creation, revenue creation for the government," he said.The congressman said the Obama administration has been better than the Bush administration when it comes to federal involvement in the issue, noting that there has been a move away from raids of legal buying clubs.
"However, they've still been causing some trouble around the edges for what we still feel are fundamentally legal state businesses," he said, adding that a "general fear" remains.
"We really can't have this be at the whim of what side of the bed a president or an attorney general wakes up on," he said.
Polis was also asked if he has any trouble getting people to take the issue seriously. When asked about legalization in 2009, President Obama laughed off the question.
"Well, I mean, it's as serious as any other issue," Polis said, adding: "I don't see anything funny about it."