The line I always assumed was that one wasn't "in the country" until one had passed customs and immigration. So where is "one" until that point? For example, let's say I land at EWR but get held up at immigration for a period totalling more than a day. Where am I? The US immigration services would not acknowledge that I am "in the United States" yet and would treat me as such. If I flew from the UK they wouldn't assume that I am still in the UK because I am clearly not, even if I fail to clear immigration (then I would be sent back to the UK) even though I am clearly, geographically, in the US. I would sent back to the UK. The same is presumably true of any other person who has not yet cleared immigration in their country of destination, and their are famous cases of people residing in airports as "stateless" persons for long periods. I can't see any country acknowledging that airside of an airport on its soil is not within the country, and that it is a stateless location through which anyone can wander without recourse or absolution from local laws???

Essentially, I am asking at which point being geographically in a country and being legally in a country resolves itself.