Canada and Ireland: Extraterritorial bedfellows

One of the least surprising legal problems encountered online is the question of which law applies where and to whom. If I post something to the internet from my home in Nebraska that is perfectly legal to post in Nebraska and the United States, but doing so violates German law and harms a German citizen living in Britain, can that individual sue me under German law? If so, where? And if he prevails, in what countries can he enforce that judgement against me? Over the past 30 years or so, we have somewhat answered these questions. To give the precise legal answer: Things basically work as one would expect, except when they don’t.