Here are two different perspectives on the German coin seizures.
The first is from David Welsh: http://classicalcoins.blogspot.com/2009/02/die-wacht-am-rhein.html
The second is from Nathan Elkins: http://coinarchaeology.blogspot.com/2009/02/police-action-with-antiquities-and.html
In my opinion, German police are entitled to enforce German law, but at the same time, it is gross overkill to seize an entire coin collection based on a few coins purchased openly on a commercial website like eBay that allegedly came from an illicit source. The" little guy" simply does not have the financial resources to contest these seizures or the stomach to stand up to police intimidation that demands a collector surrender his entire collection to avoid possible prosecution.