Researchers wanted to see if California’s legal pot shops were selling to minors. They found a 100% compliance rate.

Despite concerns that legalization would expand teen access to marijuana, a new study from the Insurance Institute for Highway Safety has found that California’s legal retailers are careful not sell their products to minors.

IIHS sent “pseudo-underage patrons” into the field to test the dispensaries’ adherence to the law. These were individuals aged 21 or over who appeared to be underage. They visited 47 shops.

“In the 47 observations that were made, the pseudo-underage patrons were never able to enter an outlet without showing identification indicating they were 21 or older (a 100% compliance rate). At about half of the outlets visited, the ID was checked before entry, and at the other half, the ID was checked as the person entered. In two of the observations, customers were seen using products inside the store. In one of these cases, the store being observed was offering free samples of edibles, which is illegal in California,” according to the report.

A 100% compliance rate is a rarity in any industry. It suggests the cannabis industry, which is still relatively new, is exceptionally careful not to attract the attention of authorities. It's consistent with a previous study from the National Survey of Drug Use and Health (NSDUH), which showed no significant change in past-month teen marijuana use in states that had legalized marijuana.

The latest findings provide further evidence for cannabis advocates who wish to see an expanded, regulated market.