Canadian residents who use cannabis run the risk of being denied entry into the United States. After claims of some residents of southeast Saskatchewan being turned away at the border, Golden West Radio reached out to US Customs and Border Protection for clarification on the rules. While they weren't available for an interview, they did provide written answers to our questions.
When it comes to entering the United States, officers with the US CBP determine the eligibility of those looking to cross the border. There are more than 60 grounds of inadmissibility to the United States, and they vary across a number of topics including health-related reasons, prior criminal convictions, security reasons, public charge, labour certification, illegal entrants and immigration violations, documentation requirements and miscellaneous grounds.
In the exhaustive list, it does state those who admit to committing a violation of any law of the United States relating to a controlled substance, such as cannabis. While Cannabis may be legal in Canada, it is still illegal under federal law in the United States, and the officers do have the ability to deny entry to the country for that reason.
Other reasons which a person can be denied entry into the United States include not being vaccinated for a number of diseases, including mumps, measles, tetanus, polio and more, someone with a communicable disease, or practicing polygamists. You can read the full list here.
Those who have been denied entry to the United States do have an avenue of appeal. The Traveler Redress Inquiry Program allows those who have been denied entry into or exit from the United States at a port of entry to have a further inquiry into why they were denied entry.