Originally Posted by
Christopher
Probably because it is not against US law for a US citizen to smoke marijuana in Amsterdam.
Have a look at title 46, ch 38 § 1903 of the US code. There is a prohibition on possession with intent to manufacture applying to all US citizens of any vessel worldwide. Note that the vessel need not be a "US vessel" if a US citizen is on board. Consequently, if a US person carrying seeds steps on a boat in Amsterdam, they are violating section 1903 of the US code. I'm quite surprised to be hearing recently that US law stretches worldwide.
I haven't found the more relevant code yet.. dealing with possession of mj w/ intent to use. It would be interesting to verify that it excludes Amsterdam, as you've suggested.