Trafficking in America is covered by the Mann Act which is the same one that captured Chuck Berry.
Including the third party - the person to whom the woman is trafficked - is difficult legislation to draw.
As this article observes, the Mann Act could be interpreted as criminalising consensual sex.
You are therefore relying on prosecutors using the legislation responsibly.
If Andrew did as alleged - had apparently consensual sex with a trafficked woman - he must be in the frame for a Mann Act offence.
You can see why he is less than eager to cross the Atlantic to speak to American prosecutors.
https://www.history.com/this-day-in-history/congress-passes-mann-act