Either the authorities are doing a better job of deterring criminals, criminals are doing a better job of out-foxing authorities, or a little bit of both.

According to a study published by U.S. News and World Report, fewer packages of marijuana are being intercepted by the government authorities, and this is being interpreted as a direct result of legalization and regulation in Colorado and Washington. The U.S. Postal Inspection Service (USPIS), the folks who generally catch illegal mailers, saw a 12 percent drop in domestic weed smuggling in 2014.

“We investigate any and all suspicious packages that contain illegal narcotics,” said Lori McCallister, a spokesperson of USPIS. The report is yet another piece of evidence supporting the argument that lifting prohibition will reduce drug-related crimes. It now looks like the growing legal marijuana market is reducing marijuana-related crimes through the mail. A DEA report found that for the first time in nearly three decades, the agency actually seized less marijuana – which is a big deal, especially with only two states lifting prohibition of the drug. Interestingly, the Rocky Mountain High Intensity Drug Trafficking Area (HIDTA) reported an increase in marijuana shipments from Colorado. McCallister says the findings are not consistent with those from the USPIS.

Mason Tvert, a Colorado-based spokesman for the Marijuana Policy Project, believes marijuana users are changing their behavior because of regulation:

“Marijuana prohibition is basically marijuana anarchy, and when there’s anarchy, it feels like nobody’s watching and you can get away with anything. Now that marijuana is being regulated, it feels like it is under control and you will likely get caught if you break the law.” Well, that’s not exactly a scientific claim – you feel like you will likely get caught if you break the law – but there might be some truth to it. But here’s another unscientific claim: every state in the union is probably smoking bud from Colorado, Washington and California.

You can read the detailed report on weed going postal here.