Originally Posted by
Dubai Stu
. US-CBP has a very high end scanner which compares the document with known exemplars of genuine, counterfeit, and altered passports from virtually every country (and other passport issuing entities such as the UN Refugee agency).
This is very true and DHS' document library grows by thousands of items every day, not just of genuine, counterfeit, and altered passports, but also of any and all travel and identity documents it can get its hands on, including visa stamps. It is an impressive operation.