The numismatist Dr. Ursula Kampmann (known by many English speakers from her site CoinsWeekly) is promoting an online petition to protest a proposed German law concerning the Protection of Cultural Heritage. If passed, the law, she contends, would potentially impose onerous burdens upon collectors to prove that their holdings have legitimate provenance. While the concerns focus on coin collecting, they would apply equally to stamps, currency, and other paper artifacts.
Dr. Kampmann is a well-regarded figure in numismatics, and her concerns are worthy of serious consideration. A description of the legislation can be found at the CoinsWeekly site; the online petition is here, and can be signed by supporters of any nationality.