Remember that extradition treaties exist. Kim Dotcom, founder of Megaupload, is a New Zealand citizen who has never lived in the United States, who was neverthe

Remember that extradition treaties exist. Kim Dotcom, founder of Megaupload, is a New Zealand citizen who has never lived in the United States, who was nevertheless pursued by the United States for breaking US copyright law (through acts that were — as far as any lawyer has been able to ascertain — not illegal according to NZ law!) According to the NZ supreme court, Dotcom can (will?) be extradited to the US to face those charges. In effect, in a world where extradition treaties exist, the law you're subject to is the sum of the laws of all the countries your country has agreed to mutual extradition with. (And strangely enough, I believe this is even transitive. Presuming countries {A,B,C} which have extradition treaties AB and BC, if country B can get you extradited from country A for crime 1, then country C can get you double-extradited during your detainment in country B for crime 2 — even though country A may have never signed any treaties with country C!) But even ignoring extradition... when speaking of international diplomatic relations, the law-in-practice of "whatever country you're in" is often not the law-as-written, but rather "whatever it takes to make a foreign country happy." I.e. if a foreign country wants you punished — and your own country isn't so powerful as to be able to just tune them out — then often you will be slapped with whatever local law your own country can make fit, to get the other country to calm down. I brought up the president of Turkiye for a specific reason: the https://en.wikipedia.org/wiki/B%C3%B6hmermann_affair https://en.wikipedia.org/wiki/B%C3%B6hmermann_affair , where a German who wrote an insulting poem about Erdoğan, was charged with a [rarely used, archaic] crime by the German government, after the Turkish government basically sent a strongly-worded letter to the German government implying that their relations would be damaged unless they "did something." (Though, pleasantly, after much outcry from the German populace, the law they used to try to punish Böhmermann was challenged and repealed: https://www.npr.org/sections/thetwo-way/2017/01/25/511611581/germany-is-scrapping-law-that-bans-insulting-foreign-leaders https://www.npr.org/sections/thetwo-way/2017/01/25/511611581...)