Rhetorical question.If the citizenship of the person is in question, do you apply Constitutional law if they are on US soil?

We also need a fool proof way of guaranteeing US Citizenship before registering for school, getting medical care, welfare, AFDC, WICA, etc...Maybe a legitimate Birth Certificate?!?

A Filipino who is married to an alien retains their Philippine citizenship, unless by their act or omission they are deemed to have renounced their Philippine citizenship.

As I have dual citizenship, the second being British, it seems intuitive to start investing in europe.

"US Citizenship" is not one of our tenant screening requirements. 

^^^^^ Those guys are much better for tax implications it looks like, but from a guy in the loan world, you'll basically just want to structure your business entity (likely an LLC) to where you can take advantage of your U.S. citizenship regarding loan terms. 

Finally, I must say that I prefer the elimination of the income tax and its replacement with a citizenship tax.

(I've seen some people do Mexico and south america) I can get my dual citizenship in Germany so I've pondered the idea since I may move there one day.Haven't found much anywhere on investing in Europe though, so anyone who can share anything would be very helpful.

No verification of experience, no criminal background check, no verification of education, no citizenship check, etc?

I think citizenship in these countries to add to a portfolio elsewhere as a hedged risk would be a terrific path, and one that I plan to explore once my US portfolio turns in to an empire in the next decade.