PNG has issued a press release indicating that it has renewed its commitment to fight against the imposition of import restrictions on coins. See: http://www.coinlink.com/News/general-collecting/professional-numismatists-guild-assists-in-combating-coin-import-restrictions/
PNG mainly represents U.S. coin dealers that sell U.S. coins. PNG also has concerns with issues such as Chinese counterfeits of U.S. coins. See http://culturalpropertyobserver.blogspot.com/2008/12/scary-counterfeit-coins-from-china.html
Given these other concerns, PNG's decision underscores the severe practical problems that import restrictions raise for the small businesses of the numismatic trade. Producing invoices is one thing. Documenting a coin's whereabouts potentially back 5 or more years is something entirely different, particularly when you are seeking that information about large numbers of low value artifacts like coins, from foreign sellers who can more easily sell to some other foreign buyer without such "red tape." Indeed, such information may not even be available at all.
This problem is exacerbated because U.S. customs has relied upon archaeologists with an axe to grind against collectors to help them detect and identify illicit "cultural property." This, of course, is a recipe for unfair enforcement.
To date, import restrictions have been imposed on ancient coins of Cypriot and Chinese type. The State Department has previously rejected calls for similar restrictions on ancient coins of Italian type.
PNG has also joined another trade group, IAPN, and the ACCG in seeking more information about such import restrictions in an ongoing Freedom of Information Act case.