You should check out how labeling works. I deal a lot with the ARRA (American Recovery and Reinvestment Act) and its Buy American provisions, and also the Buy American act.
For anything to be called 'Made in the USA' there is a certain percentage of the materials of the product needing to be sourced on American soil, and then final assembly of 'most significant' transformation has to take place in the US. Sub-assemblies can be made elsewhere, particularly in countries with which the US has a trade agreement.
I can't imagine any of this would be less complicated in Germany... That's a slightly facetious comment, because the US is the master of bureaucracy. But it's probably complicated in most countries, is what I'm saying.