Marijuana-related offenses decreased by a whopping 77 percent between 2012 and 2013, according to a Denver Post analysis of data provided by the Colorado Judicial Branch.

According to the Post’s report, the most noticeable decline was related to the number of people who were charged with petty marijuana possession, which dropped from an average of 714 per month during the first nine months of 2012, to 133 per month during the same time time frame in 2013, or by about 81 percent.

Though the Post acknowledged that the decline in marijuana-related crimes was partly a result of the state’s voters opting to legalize possession of up to an ounce of marijuana for adults 21 and older, the newspaper says its analysis of records also found that state prosecutors were pursuing far fewer cases involving marijuana crimes that remain illegal in the state.

For example, the number of people charged with possessing more than 12 ounces of marijuana dropped by 73 percent and cases involving alleged possession of fewer than 5 pounds of marijuana with intent to distribute decreased by 70 percent.

Even though the Denver Police Department has increased the number of citations issued for public consumption of marijuana, public consumption citations were down by 17 percent statewide, and marijuana-related prosecutions for those under the age of 21 also declined.

While legalization advocates have largely praised the findings, as well as racial equality groups such the American Civil Liberties Union, who say that black and Latino men were arrested and charged with marijuana-related crimes more than any other group, Colorado Attorney General John Suthers said he thought the decrease in cases could be related to local law enforcement’s confusion about the new marijuana law.

“I think they’ve kind of thrown their arms up in the air,” he said.

Tom Raynes, the executive director of the Colorado District Attorneys Council, agreed with Suthers’ claim that the state’s new law is making it difficult for law enforcement and prosecutors to police and prosecute marijuana-related crimes, since “police are no longer allowed to investigate in depth purely because they smell pot.”

“With small quantities especially,” he said, “I think law enforcement feels like they don’t know which way to turn.”

Although the Post says its analysis wasn’t all-inclusive, since drug charges can be filed in municipal courts that aren’t included in the data the Colorado Judicial Branch provided, if the reason there has been such a dramatic decrease in crime is because police are not sure how the law works, Colorado may be in trouble with the Justice Department.

When Colorado legalized marijuana, that state law was in direct violation of the Controlled Substances Act, which classifies marijuana as a Schedule I drug. It wasn’t until September 2013 that state lawmakers knew that the DOJ would not file a lawsuit for failing to follow federal law.

But the DOJ’s announcement that it had deferred its legal right to challenge the marijuana legalization law, at least in the interim, came with a big if, as in if the state were to implement a well-regulated system that would respect the federal Controlled Substances Act, then the DOJ wouldn’t file its lawsuit.

If the DOJ catches word that local law enforcement and prosecutors in Colorado are unsure of the law and are therefore unable to do their jobs, marijuana legalization in the Rocky Mountain state may be in jeopardy.