A review by criminologist Sawyer Sylvester of Simon Mackenzie and Penny Green (eds) 2009, 'Criminology and archaeology: Studies in Looted Antiquities', Oxford and Portland. I've not seen the book itself yet, but it looks useful.
Notable quote from the review about the trade in the UK:
But perhaps most problematic of all was the relative lack of will and resources put forth by the government compared to the money, influence, and legal talent available to museums, collectors, and art dealers.
I think this is a more general problem isn't it?