bredin wrote:I rather think they do consider themselves able to pass such a law.
I'm not an expert but I think it is not legal on an international level. There are similar laws in France (for tax only), but if you look closer with the help of a specialized lawyer, you can find out they are simply *illegal*... A law, being illegal, funny?
I don't recall what the exact term is, but there are agreements between countries to avoid double taxation. There are criteria to select which country will collect your tax (work, duration of stay, etc), if this cannot be determined by those factors, it's (more or less) up to you to declare your income to one or the other.
Once your incomes are declared (and taxed) to one country, the other cannot claim the same. For example (whatever the patriot act says): if you work in France, and reside in the country for more than 6 month, then you will be taxed under the French system, for the relevant fiscal year. There is no derogation to that (?), and once you have paid your tax to one country, you can't pay it a second time to another (even if they would like it!).
Most of the countries have similar regulations in regard to taxation of foreign nationals.
What every country want, just tax anybody to death, by any means necessary. This is what I hate about the system, they steal the money of honest citizens and businesses who simply pay their tax without asking any questions... They make more money taxing struggling citizens (due to their number) than multinational companies. Because the multinational company has a team of lawyers to work around that, and they won't pay a single $ more than what is strictly required.
Now about that leverage thing, if an American citizen wants to trade 400:1 on an Asian broker, who will stop him?