Marijuana workers and investors from Canada may find themselves under a lifetime ban from the US if they plan a visit anytime soon.

Federal laws stand in the way of the United States extending reasonable treatment to workers and investors who plan to be part of the legal marijuana industry in Canada. In fact, despite the fact that the drug will be legal across the border, anyone who has a connection to marijuana in Canada will be treated as a drug trafficker should they choose to enter the United States, according to US Customs and Border Protection agents in mid-September.

The United States has nine states where recreational use of marijuana is legal, and 30 states where medical treatment via marijuana is permitted. Despite this show of growing tolerance at the state level, workers and investors from Canada may find themselves under a lifetime ban from the US if they plan a visit anytime soon. Customs agents won’t hesitate to hand out the bans.

For those who hope to visit, it’s advised to not answer the question regarding marijuana use. This may still result in denial of entry, but instead of a lifetime, it would be for a single day.

This topic came to light earlier in the summer since Ottawa announced the legalization of marijuana for recreational use — countrywide legalization is slated for October 17. It’s important to know that smoking in the vehicle can be detected for weeks afterward, making it a long-lasting concern for anyone planning a trip to the US in the future.

Meanwhile, marijuana is not recognized as a legal business at the federal level. Investors from other countries have already been denied entry to the US as a result. With the precedent in place, it’s logical that the treatment would extend to a country that shares a land border. However, the announcement received a surprising widespread reception.

As a result, stocks have dropped. From Tilray (NASDAQ: TLRY), which recently announced plans to export marijuana buds to Germany for medical treatment use, to Cronos Group (TSE: CRON), which is focusing on distribution that will be ethical and avoid marketing techniques that might appeal to a younger audience. These companies, along with others, were seeing positive stock growth prior to the most recent announcement.