Marijuana is a short-cut that police have been abusing for years to justify illegal searches of cars. That is what they’re really up in arms about.

Unlike many drugs, marijuana has a very pungent and distinctive odor to it. An officer can’t justify a search by lying and claiming to smell cocaine. Where marijuana is illegal, police can search any vehicle or person they want simply by lying and saying they smell marijuana. Even if the search turns up nothing, that does not make the search invalid. The officer can simply claim they were mistaken. The barrier to justifying a search is rather low. It’s impossible to prove the officer is lying. You can’t prove they didn’t smell marijuana. Marijuana is a tool that cops can use to flagrantly violate the 4th Amendment.

This is the real reason police oppose marijuana legalization.