As 2016 starts, crime is up yet again in the post-marijuana legalization metropolis of Denver, Colorado.

The latest data shows that reported offenses during January 2016 increased a further 4.5% from the same month in 2015.  This continues a consistent trend seen since the state's marijuana legalization process started in mid-2013.

During 2015, total reported crime increased 4.1% over 2014, with the number of murders up 74%, aggravated assaults up 14%, forcible sexual offenses up 8%, and non-forcible sex offenses up 39%.

In 2012, the year before the legalization framework was brought into force, there were 44,338 total reported crimes in Denver. Last year, this number hit 63,816, an increase of nearly 20,000 crimes per year – 44% higher than in the pre-legal pot era.

Population increase doesn't come close to explaining the trend. Annual growth rates for population in the Denver and Metro Denver areas have been consistent at just 2% over this period, meaning the crime rate is rising rapidly.

And yet, somehow the Denver Post claims that "in any given year, marijuana-related crimes in Denver make up less than 1 percent of all offenses counted in the Uniform Crime Report and less than a half-percent of all NIBRS offenses."

There is no reliable way to determine what percentage of the reported crimes are due to marijuana legalization.  Some offenses, when investigated by authorities, will show an unequivocal direct cause to marijuana use.  But it is simply impossible to accurately measure all offenses directly caused by pot use.

If an individual engages in criminal activity either under the influence of marijuana, or in some direct manner related to marijuana (e.g., in order to steal something to pay for marijuana use, etc.), this cannot be determined unless (1) the police fully investigate all reported offenses, both minor and serious (which they do not), and (2) the perpetrator is caught and successfully prosecuted, having the facts – including any relation to marijuana – clearly established beyond a reasonable doubt in court (which is an even smaller percentage of total reported crimes).

Consequently, the low rate of proven direct associations between crime in Denver and marijuana use is expected, and it tells us nothing about the actual direct causes of marijuana use on crime in the region.  It is simply an unknowable question.

Equally important is the indirect effect of marijuana use.  The legalization of pot sends a powerful anti-societal message to many, and its use can lead to socio-economic decline for individuals and families – the results of which may take a long period to show their real effects and be essentially impossible to link to marijuana use without a suite of equally long (and expensive) case studies.  We lack the resources for these investigations, and, as a result, absence of evidence is not evidence of absence.

The Post's article even acknowledges the limitations of the city's cursory investigation: "The numbers are for more serious offenses and do not include petty citations for violations such as public marijuana consumption, nor do they include crimes committed by juveniles."  In other words, we don't know what we don't know.

But what we do know is that the number of crimes in Denver skyrocketed started at the same time the legalized marijuana policy was implemented, and this empirical evidence, combined with what science tells us about the harmful psychological effects of marijuana use, is, while not conclusive, strongly suggestive that the social fabric is starting to unravel in the Mile-High City due to pot legalization.

And now we see that "Colorado's Governor is cautioning other states from legalizing marijuana."  According to a report by Channel 7 ABC in Denver, Gov. John Hickenlooper made the following statements at a conference in Dallas on Tuesday:

You get all those young people who do certain things that some of us oppose and aren't crazy about, like legalizing marijuana. Let me tell you, if you're trying to encourage businesses to move to your state, some of the larger businesses, think twice about legalizing marijuana.

Looks as though the blowback from Colorado's legalized marijuana experiment is starting to cut broad and deep across the state.  All this was predicted, and there is little doubt that the net societal costs of legal pot far outweigh the modest tax revenues being collected off sales of the drug.