This will cause a lot of trouble, to say the least. Crossing the border has always been a tense experience. For the thousands of Canadians who will be joining the legalized cannabis industry, it’s going to become even more harrowing.

Even though cannabis has been legalized for recreational or medical use in 30 U.S. states, the federal government still views it as a controlled substance. American border guards have immense latitude over who they let enter the country. If you’re not a U.S. citizen or a permanent resident, your rights at the border are very limited. Border guards have every right to ask you about your employment, drug use or even your investments.

It doesn’t matter where you’re crossing over. Even if you’re trying to enter a state like Washington or Maine, where cannabis is legal for recreational use, you can still be denied entry. Border guards work for the feds.