Top police officials in Boston and New York City made comments about marijuana this week that demonstrate again why law enforcement has so little credibility on the subject. One was hyping the dangers of marijuana legalization, the other was using a trope too clever by half to describe a non-marijuana drug threat.

1. Boston Police Commissioner William Evans

Evans told the Boston Herald Monday that he was concerned about legalization because of the alleged link between pot and home invasion robberies.

"A lot of home invasions seem to revolve around someone smoking marijuana, young college kids tying to supplement their income," he said. "We get a half-dozen every year where they invite regular city kids over and next thing you know, their door is getting knocked down and they are getting robbed."

And he worried for medical marijuana patients.

"I worry about someone picking up their [medical marijuana] supply, walking two blocks down the street, and someone else there waiting to rob them," Evans said.

The glaring point Evans can't see is that if marijuana is legalized, people won't be breaking into homes to steal weed, they'll be going to the pot shop to buy it. Likewise with medical marijuana: If marijuana is legal, no one has any reason to steal it from patients.

Granted, there could still be problems with some people breaking into homes or businesses to steal legal marijuana. It would likely be on the same level as the problems we face with people breaking into homes or businesses to steal alcohol or anything else of value. In those cases, we don’t blame the valuable item; we blame the criminal.

Evans even threw in a bonus stupid statement. "There is no doubt in my mind it’s a gateway drug," he proclaimed.

That theory has been debunked repeatedly, including here, here, and here.

2. New York City Police Commissioner William Bratton

Bratton held a Tuesday press conference to warn of the dangers of a new psychoactive substance, a synthetic cannabinoid police say gives users superhuman strength and makes them impervious to pain.

Let's forget the whole "superhuman strength" and "impervious to pain" language, which is eerily reminiscent of descriptions of black cocaine users in the 1910s and PCP users in the 1970s. It's the way Bratton described the substance itself that is so wrongheaded.

The synthetic cannabinoid is "weaponized marijuana," is how he described it. (To be fair, it is not crystal clear from various press accounts whether Bratton used the phrase "weaponized marijuana" or whether police are just calling it that.) The phraseology is problematic for a couple of reasons. First, and most obvious, synthetic cannabinoids are not marijuana. They are chemicals manufactured in laboratories, not products of the cannabis plant. While even common terms for the stuff, such as "fake weed," are also misleading, they at least acknowledge that what is being referred to is not real marijuana.

Synthetic cannabinoids have a single cannabinoid in them, unlike raw marijuana, which contains hundreds of distinct compounds. That may account for some of the adverse effects associated with the synthetic cannabinoids; they do not contain the entire spectrum of cannabinoids found in real pot.

The second problem is the use of the term, "weaponized," which is essentially meaningless. If Bratton means it "can have adverse effects," he should have said that. Calling a psychoactive substance "weaponized" is not only a bad metaphor, it's also deliberate fear-mongering.

Law enforcement claims expertise on drugs and drug policy presumably because law enforcement has to deal with drug offenses. Law enforcement also has to deal with domestic violence, but that doesn't make cops experts on marital relationships. The comments by these two big-city top cops this week suggest we shouldn't be listening to them when it comes to pot policy, either.