The infamous Overzealous US Customs official and the Auction Catalogues'. This lacks any support in the literature apart from unsubstantiated anecdotes reportedly originating from a single (interested) 'source' and constantly repeated by a single lobbyist who calls on the first ('a recently retired official in CBP's New York office') as an 'authority'.
I followed this up here: 'Purpose: Only to Sow Confusion?' PACHI Monday, 28 April 2014. This is exactly what the antiquitists' lobbyists are doing. If US Customs really is engaging in extra-legal activity, it is the duty of the dealers associations to step in and support any of its members thus affected, by instituting a court case against the ICE. That is precisely what associations and guilds like the ACCG exist for. Yet, though the unsubstantiated accusations fly, not a single case has been brought before any court.