This is an example of extra-territorial legal enforcement. In the age of globalisation and the internet, legal lines can get blurred.
As a Canadian working in Europe, for an American company, my actions in the market are tempered by the US FCPA as well as Anti-Trust laws. So I cannot engage in bribery or price-fixing, else the mother company in the US could be sued and fined. In Europe, they have similar laws as well, so we could effectively nailed in both directions (c'mon Gangs, here is your opening).
The reason for this is that in the past, companies would open separate legal entities, and then bahave very differently in foreign markets (up to the point of AT&T assasinating executives of competitors in some South American countries in the 50s and 60s), creating local monopolies, and generally fostering corruption worldwide. This actually hurt the companies involved, and especially the consumers, so the laws are enforced this way to ensure US businesses are kept in a constant state of competition and relatively honest - a departure rather than a continuation of pre-1945 imperialism that led to the 2 big wars.
It hurt them because noone had a high moral ground to stand on to tamp down on corruption, which meant the fight was symetrical, and therefore bloody. It also gives a more positive image for America abroad, and is fundamentally in line with the Yalta agreement. The EU, just having been formed, has followed suit, and now has similar laws, so an EU based company operating in China is subject to EU Competition Law. This process has proven itself because despite these "restrictions", US companies have thrived everywhere, and because the consumer benefits, the local economies grow rather than get crushed by monopolies. US companies are there for the long haul, and no longer seen as part of the problem. A different kind of empire.
That said, Sometimes the US goes too far, as in the Helms-Burton Act, in which the assets of Canadian companies operating in the US can be seized if they profited from the purchase of Cuban lands owned by the US prior to the revolution. Executives travelling through the US can be imprisoned as well. Basically they are held accountable for the value of the Cuban assets, as well as all profits generated from them since they were sold to the Canadian firms by Castro, who nationalised them in 1960 (or thereabouts).
The Canadian response at the time that this law was being passed was stellar: The Canadian government agreed with Helms-Burton, and offered support for drafting an airtight law, to ensure a strong dispute resolution process and continuation of our long-standing legal co-operation (which is of course the basis of ensuring a good trade partnership). Senators Helms and Burton were taken a little aback, but could not refuse the offer. When they met, the Canadian legal minister went through the draft with them, and they agreed on pretty much everything, and at the end reminded the US senators that both of our legal systems are based on precedence, and that once a precedent is established, it can open the door to other lawsuits ie from other geographies. Then he presented tot hem the original deeds to the lands of the loyalists from the 13 colonies who fled to Canada after the American Revolution, and using the same calculation, the bill would astronomical.
So Helms-Burton is enforced tentatively, and held in check by the threat of establishing an unfavourable precedent...
OK, Llamavore, compete with this wall of text.