I am a Russian citizen living in the Netherlands, my travel plans for this year include many EU countries, many trips to Russia as well as UK, US and Japan. At the moment, I have never done drugs, but I have been to coffeeshops with others. Recently, my bags have been drug tested in Warsaw airport. The test came out negative but that got me thinking:

  • Many countries criminalize purchase of cannabis
  • Many countries have the legal concept that a crime committed abroad is equivalent to a crime committed on their soil
  • If I were a frequent visitor of Dutch coffeeshops I could easily have trace amounts of weed on my clothes and backpack which could be detected.

Are there notable precedents of travellers punished for doing drugs in a country where it's legal? If any of my stuff ever tests positive on a drug test in a country where it's illegal will telling the police that I have been to a coffeeshop in the Netherlands help me or hurt me? Should I establish a "quarantine rule" of not coming close to anything drug-related N days before I leave the Netherlands? How many days? Which countries should I be especially cautious about?

  • 22
    Excuse for what? My hypothetical is not about actually carrying any drugs abroad - it's "can I run into trouble just because the police suspects I did drugs in the Netherlands"
    – 0x60
    Commented Feb 25, 2020 at 13:56
  • 17
    It's nitpicking, but using drugs is often not even illegal, in many codes it's the possession.
    – JakeDot
    Commented Feb 25, 2020 at 14:02
  • 17
    @Traveller "If you test positive, they won’t care why or where." Really? Surely, a trafficker with his bag full of cocaine will be treated differently from someone who stayed over with a smoker friend, as in your example. Both can have their luggage test positive. So circumstances should matter, right?
    – 0x60
    Commented Feb 25, 2020 at 14:04
  • 4
    @Traveller If I can't identify any drugs on my stuff, but a sophisticated chemical test can, does that count as posession?
    – 0x60
    Commented Feb 25, 2020 at 14:14
  • 3
    I think this is way too broad for the SE model, with too many cases and variables, and ultimately, too many opinions. I voted to close. Commented Feb 25, 2020 at 16:00

4 Answers 4


As an avid watcher of Border Security, I can tell you that when cocaine or other illegal drugs are detected by a swab (I never saw any swabbing for pot), this gives them a good reason to search the heck out of your bags, but if you aren't carrying, that's an end to it. I saw this at the US border, Canadian border, and Australian border. The Canadian border officers repeatedly said "we don't care what you do on your own time, just what you're bringing in, were you around people doing x?" but I did notice that saying "yes, I was" didn't stop the search or actually seem to be of any benefit to the traveler, except perhaps establishing them as honest and co-operative. At the land border, smelling pot on a person or their possessions definitely led to thorough searching of vehicles. So for a lot of countries, the "answers" in the comments above are generally true: as long as you're not carrying, they won't care that you used it before you arrived. (Side note: the lack of caring is not related to whether or not it's legal where you used it. Border officers are famous for not caring AT ALL about the laws elsewhere, only in their jurisdiction.)

However, this is not a general rule. Singapore can (and apparently does) do drug tests on arrival and arrest people based on blood levels.

“Any Singapore Citizen or Permanent Resident found to have abused controlled drugs overseas will be treated as if he/she had abused drugs in Singapore,” the statement read. “CNB conducts enforcement checks at Singapore’s checkpoints and will take action against those found to have consumed drugs overseas.” - Singapore Central Narcotics Bureau

(The government of Canada later added that they feel this applies to foreigners also.)

Also from that article, since you asked about a quarantine period:

According to the Mayo Clinic, cannabis can be detected in urine three days after use for an occasional user (three times a week), 10 to 15 days for a daily user, or more than 30 days for a heavy chronic user (multiple times a day). For a blood test, it is typically detectable for one to two days, but can increase with more use, and saliva testing it is detectable for one to three days for occasional users. That number rises to 29 days for heavy users, according to Heathline.

Most of the articles I found about this included phrases like "the most serious anti drug policies in the world" or "famously strict drug policies" so don't assume Singapore is typical. There might not be any other countries doing it. But -- there might. Also, back in your own country, if there are drug tests related to employment, child custody, security clearances or whatnot, nobody is going to care "but it was legal where I was!" If it is illegal where they are testing, there will be consequences for testing positive even if you didn't break any laws.

  • 15
    Japanese citizens (not sure about Permanent Residents) also can be arrested for having consumed overseas, but not tourists. (Source: Watched drug-sniffing dog segments on Japanese TV shows.)
    – Ken Y-N
    Commented Feb 26, 2020 at 0:00
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    The trouble is, the detction threshold for cannibis is much longer than you say, and can be detcted 6 months out. With hair testing, as long as your hair is. Commented Feb 26, 2020 at 13:50
  • 1
    I've heard that. I would appreciate references. The quote in my answer is from a news article that asked a qualified source. This is non theoretical for me - cannabis is legal here, and I have family who want to visit Singapore and worry about blood levels. They have mentioned 6 months also. But nobody has a source or reference. If you have one, @Harper-ReinstateMonica, please share it. Commented Feb 26, 2020 at 14:13
  • 3
    I knew some Korean students in college. They all told me that they are drug tested upon their return to Korea and that they would get in legal trouble if they smoked cannabis in the US, even if it was legal (state law) when they did it.
    – user101401
    Commented Feb 26, 2020 at 20:31
  • 1
    14. Taking drugs before you enter the country : Penalties for drug possession in Singapore range from fines as high as $20,000 to 10 years in prison. In certain cases, if the amount of the drug is high enough, the punishment can even be a death penalty. Singapore officials have the right to conduct anonymous drug tests without a warrant, so any drugs taken before you enter the country can still put you at risk. – 16 odd things that are illegal in Singapore, businessinsider.com/things-that-are-illegal-in-singapore-2015-7
    – Mazura
    Commented Feb 27, 2020 at 1:15

Some jurisdictions can take a very stern view to ANY suggestion of recent past drug use.

A few years ago a British citizen was arrested on arrival in Dubai for having 0.003g of cannabis embedded in the dirt on the bottom of his shoe. He was jailed for 4 years, before being pardoned after a few months. Source: BBC news.

The same story mentions several other cases, including a Swiss citizen, also jailed for 4 years, for having 3 poppy seeds from a bread roll on his clothing.

  • 13
    technically, those stories refer to people importing drugs into those countries, not to past use. Still draconian to be sure. Commented Feb 25, 2020 at 20:52
  • 11
    @KateGregory True, but jailing someone for importing 3 poppy seeds from a bread roll, possibly because of the association of poppies with heroin, is a pretty extreme conclusion in my opinion.
    – Nick
    Commented Feb 25, 2020 at 20:57
  • 31
    The poppy seed example is especially heinous: poppy seeds aren't a drug and don't contain any drugs. The problem is that many tests for opiates don't actually test for opiates; instead, they test for certain proteins which are present in the entire plant.
    – Martha
    Commented Feb 25, 2020 at 22:24
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    @KateGregory the question also asks about belongings testing positive for trace amounts due to being around it, which this answer definitely applies to.
    – Kat
    Commented Feb 26, 2020 at 3:32
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    @VladimirF: no, that's precisely what I'm saying. Poppy seeds do not contain any opiates, but they do show up on drug tests, because those tests do not actually test for the presence of opiates. It's like, I dunno, looking for bread, but actually testing for yeast, and thus giving false positives for beer.
    – Martha
    Commented Feb 26, 2020 at 16:03

In South Korea you can go to jail if you smoked Marijuana in a country where it is legal (like Canada or the Netherlands). Some K-pop stars were send to jail for smoking weed in the Netherlands.


NY Times post

Fortune post

The Guardian post

  • 5
    But that applies to South Koreans only. If a, say, Polish traveller smoked weed in Netherlands and then went to Sout Korea, it would be fine.
    – Crowley
    Commented Feb 26, 2020 at 14:35
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    @Crowley yes that is true, only South Koreans are subject to Korean laws outside of S. Korea.
    – J_rite
    Commented Feb 27, 2020 at 6:43
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    @Jungkook But everybody is subject to South Korean laws in South Korea, no? Commented Feb 27, 2020 at 10:32
  • 2
    @lambshaanxy that is correct
    – J_rite
    Commented Feb 27, 2020 at 10:57
  • @lambshaanxy American soldiers aren't, when on official duty: en.wikipedia.org/wiki/Yangju_highway_incident. But the point is that if you're not a South Korean, you can't be prosecuted for acts which take place outside of South Korea (with some limited exceptions unrelated to drug use)
    – llama
    Commented Feb 27, 2020 at 20:51

You mention EU countries. Belgium doesn't care about drug use in other countries. However, it's illegal to drive a car in Belgium if there's any trace of previous drug use in your blood, and obviously the country of drug use doesn't matter. Random roadside tests are uncommon, but they happen, so it's not advisable to drive a car in Belgium for weeks (or months, depending on the source) after using drugs.

  • Saliva tests are being used more and more in Belgium and they can detect "hard drugs" like cocaine, speed, meth until a few days afterwards and "soft drugs" like weed or hasj until a bit over a week (for regular users it can be longer)
    – J_rite
    Commented Feb 27, 2020 at 6:45

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