[nerdbert]

I'm not taking a position on its legality. In most cases that's undefined because the law did not anticipate this situation and it's never been tested in court.

They obviously can't prohibit people from checking emails or taking work calls while on vacation, because that means the end of big-spending tourists.

Nobody has drawn a red line at a magic point along the continuum from one emergency work call during a two-week holiday, to 9 hours a day in a hotel room hunched over a computer. Where would it be, and why does that particular point maximize benefit for the host country?