[rglovejoy]

Even if the Secret Service can find the manufacturer and serial number info in a document, how can they match this information with the end user if he/she does not turn in a warranty card?

I can think of a couple of scenarios:

1) During the driver installation process, the serial number and the user info stored on the system is (edit: could be) sent to the manufacturer. This might be defeated by using an open OS and drivers. The user could also use the printer with a system that is never connected to the Net.

2) The Secret Service would be able to track the printer down to the store where it was purchased. The retailer would be able to supply credit/debit receipts, but what if the buyer pays for the printer with cash? The Secret Service would have to rely on the store's video surveillance system (who knows how long they keep these records?) or on eyewitness descriptions from the store clerks and cashiers (which may not be too reliable).

[gojomo]

Even without the ability to trace to an exact purchaser, to be able to correlate multiple documents to the same person, or use the printer as corroborating evidence after finding a suspect by other means, would be very valuable to law enforcement.

And unless the printer is only used for disfavored purposes, its other output is in circulation. Who's to say there's not a ad hoc registry maintained by paper samples culled from filed forms or even trash dumps and recycling bins. ("That serial number was never registered but it was sold from a retail store in Cleveland in 2002 and its printouts were seen in recycling flows in Maryland in 2006.")

[eli]

Uh, I think you're giving the government's tracking and cataloging abilities way too much credit. They have trouble keeping track of a list of terrorists.

It think it's for confirming that a particular printer made a particular note (and determining how many different printers are involved in counterfeiting). Nothing more.

[mhjyfvguv]

These aren't the $49 inkjets at best buy, these are large expensive leased units in government and large companies. So when somebody leaks something embarrasing you have a better chance of finding who did it. If you are investigating a company for tax it helps to know who/when/where that document was really created.