It seems to me that American residents of Thailand would be exempt from the extraterritoriality provision, since they did not travel for illicit purposes.
And “child marriage” does not even figure into the statute. (Age-of-consent lists can be misleading, since most states allow a lower age if the couple is married–perhaps subject to approval by a judge, or if the bride is pregnant.)
I am fascinated with the problem of determining under what circumstances a marriage contracted in one country is valid in another. For example, if one country allows the bride to be nine, and then the couple move to the U.S., what happens–does the state take her away and call child services, or do they respect the other country’s decision?
In some countries there might be confusion over the recognition of polygamous marriages. Even in the U.S., which doesn’t recognize them, I wonder what happen if Sheikh X marries bride A, marries bride B, divorces bride A, moves to the USA, bride B files for divorce, and then Sheikh X objects that U.S. law does not recognize that marriage, since he was already married to A at the time of his “marriage” to B.
And what if one is “married” through a popular ritual, without signing anything at city hall? And then one person says it was a wedding, and the other says it was just an ordinary banquet? They changed the law on that here in Taiwan last year (no registration, no marriage) but…in Thailand, if you tie your hands together and take photos, that’s still considered proof of marriage, no?
On another subject, I wonder about the disparate treatment accorded to Americans who join various foreign militaries. “Johnny Jihad” joined what he thought was the army of the legitimate government of Afghanistan, only to be charged with treason or terrorism or something by the invading Americans (who tortured him, and now ban him from studying the Qur’an in prison). Meanwhile, lots of Israelis have American citizenship too, yet still serve in the Israeli army. Why isn’t the government sending THEM to special camps?