Once the federal government legalizes recreational cannabis on Oct. 17, it’ll be legal for Canadians to fly anywhere in the country with up to 30 grams of cannabis in their luggage — be it checked or carry-on bags — according to Transport Canada. However, it’ll remain illegal to ship any amount of cannabis on a flight across the Canadian border, even if it’s part of a medical prescription.

How this will all play out in the security line at Canadian airports remains to be seen. Christine Langlois, a spokesperson with the Canadian Air Transport Safety Authority — which oversees security checks at airports — said it’s still working on how to adjust its protocols. “We expect to finalize our procedures in the coming days,” Langlois said in a statement.

Several airports in the United States in regions with legal cannabis have made similar moves. Los Angeles’ LAX airport has recently allowed passengers to fly through with cannabis in their luggage, thanks to California’s legalization of the drug for personal use last January. Those 21 years or older can have up to 28.5 grams of cannabis, or eight grams of concentrated cannabis, while passing through the airport.

“However, passengers should be aware that (cannabis) laws vary state by state and they are encouraged to check the laws of the states in which they plan to travel,” reads a notice on the airport’s website.

Even if you fly from Canada to a U.S. state where cannabis is legal without being caught north of the border, there could be serious consequences.

In the United States, border security agents such as the Transportation Security Administration (TSA) and Customs and Border Protection (CBP) are governed under federal laws — even in states like Colorado and California — which still treat cannabis possession as a crime.