For South Koreans in Canada, the police in their home country have no problem harshing their mellow.

Canada became the second country in the world to legalise recreational marijuana last week, but for South Koreans hoping to try the drug, their hopes have just gone up in smoke. Police in South Korea have repeatedly told their citizens not to partake in this newfound freedom, with the latest warning coming this week.

“Weed smokers will be punished according to the Korean law, even if they did so in countries where smoking marijuana is legal. There won’t be an exception,” said Yoon Se-jin, head of the narcotics crime investigation division at Gyeonggi Nambu provincial police agency, according to the Korea Times.

South Korean law is based on the concept that laws made in Seoul still apply to citizens anywhere in the world, and violations, even while abroad, can technically lead to punishment when they return home. Those who smoke weed could face up to five years in prison.

South Korea strictly enforces drugs laws even for small amounts, and celebrities caught smoking weed are often paraded in front of media for apology tours. Officials work to project an image of a “drug-free nation” and only about 12,000 drug arrests were made in 2015 in a country of more than 50 million people.

However, details on how police would test those returning from Canada remain hazy. Experts suggested enforcement would focus more on drug traffickers than casual users.

“South Korea can’t screen everyone who visited a foreign country, but the police maintain a blacklist that leads to certain individuals being supervised,” said Lee Chang-Hoon, a professor in the department of police administration at Hannam University in Daejeon. “But the police are more concerned with the transportation of marijuana into South Korea, and the police messaging shows they are anxious about tackling this issue in the near future.”

Judges in South Korea have a significant amount of discretion and will likely assess the crimes individually, Lee added, “especially when marijuana is prescribed of medical reasons”.

There are about 23,000 South Korean students in Canada, according to statistics from the Ministry of Foreign Affairs.

Marijuana has a long history of use in making hemp fabric in South Korea and the plant was banned only in 1976 under dictator Park Chung-hee. Before prohibition only “Indian marijuana” was labelled as a narcotic and the drug was common in music and artistic circles in the 1960s and 1970s, where many took to “happy smoke”, as it was commonly called at the time, for inspiration.