by Ryan McMaken, Mises Institute

Editor’s note: In the following article, McMaken makes a point we’ve been making for a long time. Even partial legalization of maerijuana has benefits and moves the ball forward. 

The partial legalization of marijuana has not been quite ideal. Thanks to high regulatory burdens on the marijuana-production industry, limitations on production volume, and high taxes, black markets have persisted within those states that have adopted a variety of legalization measures.

Perhaps most burdensome has been ongoing federal banking regulations that essentially prohibit marijuana producers from using commercial banking services. The resulting reliance on physical cash has led in many cases to more robbery and inefficiencies within the cannabis industry.

Nevertheless, even partial legalization has brought at least some of the benefits that one would expect. Cannabis products are now subject to commercial quality control. That is, a customer who walks into a dispensary now has a much better idea of what he’s buying. When cannabis sales took place only in the black market, one could only guess as the provenance of the product, and customers had no legal recourse in cases of fraud.

One of the greatest benefits, from a laissez-faire perspective, has been the fact that legalization of marijuana has in many ways tied the hands of law enforcement.

Once upon a time, all that was necessary to justify a police search of a home or car was just a tiny amount of marijuana. Since marijuana was legalized in Colorado in 2012, police departments are finding it harder to justify many of their searches and seizures that were once routine.

Now, in a new decision announced last week, the Colorado Court of Appeals ruled that police cannot use the presence of some marijuana as probable cause for a search of a resident’s vehicle.

In other words, a law enforcement officer cannot simply assume that just because a suspect may possess some marijuana, then he or she must be in possession of illegal substances, or engaged in some illegal activity.

In other words, thanks to Amendment 64, any Colorado resident using marijuana has “a legitimate expectation of privacy” even if in possession of marijuana.

In the case Colorado vs. McKnight, the ruling hinged largely on the use of drug-sniffing dogs. If a dog “alerts” to the smell of marijuana, does this provide probable cause for a more thorough search?

The court ruled no. Moreover, the court’s ruling may even greatly restrict the use of police dogs in general since the dogs are trained to indicate the presence of what is now a legal substance.

The court concluded:

Because Amendment 64 legalized possession for personal use of one ounce or less of marijuana by persons twentyone years of age or older in Colorado, it is no longer accurate to say, at least as a matter of state law, that an alert by a dog which can detect marijuana (but not specific amounts) can reveal only the presence of “contraband.” A dog sniff could result in an alert with respect to something for which, under Colorado law, a person has a legitimate expectation of privacy, i.e., the possession of one ounce or less of marijuana for personal use.

Thanks to the partial legalization of marijuana, a dog’s alert to marijuana in Colorado might as well be an alert to a can of spray paint, or a pack of cigarettes, or to any other substance that is totally legal for adult use in the state.

Thus, so long as a dog is trained to alert to marijuana, the dog’s alert cannot provide cause for suspecting a Colorado resident is involved in illegal activity.

This is all for the best, of course, since drug-sniffing dogs are notoriously unreliable:

In U.S. v. Bentley, we see just how damaging the Harris decision really was. Lex, the drug dog that searched Bentley’s car, had a 93 percent alert rate. That is, when Lex was called to search a car, he alerted 93 percent of the time. He was basically a probable cause generator. His success rate was much lower, at 59 percent. That is, the police actually found drugs just six of the 10 times Lex told them they would. That means that four of every 10 people Lex alerted to were subjected to a thorough roadside search that produced nothing illegal.

Anything that limits the use of drug-sniffing dogs essentially limits the use of dogs to produce “probable cause” as law enforcement officers see fit.

None of this prevents the police from switching to dogs trained to not alert to marijuana, of course. In that case, police could then use dogs to create probable cause for meth, or cocaine, or any number of other substances.

However, this could be addressed by further partial legalization. The partial legalization of cocaine — say for people over 21, and in small amounts — would throw up additional barriers to police-dog tactics by rendering dog alerts to cocaine as useless for police purposes in these situations, as well.

The ruling in Colorado v. McKnight is just the latest good news that has resulted from the partial legalization of cannabis in Colorado.

Partial legalization has made it more difficult for police to justify searches of cars and homes in general. In jurisdictions where prohibition remains — see the study on Johnson County, Kansas, for example — police can declare “victory” even if a half-ounce of marijuana — or even just drug paraphernalia — is found in the wake of an expensive and dangerous raid on a home.

In a home full of multiple adults in Colorado, however, police would have to hope their raid leads to discovery of multiple full ounces of marijuana, and possibly a sizable grow room, too. No longer is it sufficient for a disgruntled resident to claim he saw the neighbor smoking a joint in his back yard. A raid on the home of a casual joint-smoker may be just as likely to net an expensive lawsuit as it is to produce a cache of illegal drugs.

By making some marijuana legal, the job of law enforcement agencies become more difficult because now they must distinguish illegal possession and sale from legal possession and sale. In effect, this neutralizes the ability of police to easily claim that any amount of drugs is justification for vehicle and home searches. While this may mean many residents are still caught up in the web of the drug war, it’s nevertheless a much smaller number than was the case under total prohibition.