Theorists will have even more to ponder following a research effort reported by the Electronic Frontier Foundation Monday, which revealed a government tracking initiative embedded in some color laser printers.
The research cracked a secret code used in certain laser printers that shows the date and time a printed document was created, as well as the serial number of the printer.
The code appears as a grid of microscopic yellow dots, each less than a millimeter in diameter.
The researchers used documents printed from the Xerox DocuColor line of printers to break the code, but the yellow dot patterns from other printers will likely use a similar code, according to a release from the foundation.
"It certainly seems like the sort of thing a government ought not to be doing in a free and open democracy," said Alison Myhra, a professor of law who specializes in privacy legislation.
"This may be the best example of where we have laws in place, and the old laws and old principles don't really work," she said.
"Internationally, that's one of the big reasons you see so many countries going to holograms, watermarks, things like that," said Ed Youngbloood, assistant professor of electronic media and communications.
The foundation provides a list of "yellow-dot" printers on their Web site, www.eff.org, as well as instructions on how to locate and view the patterns.
For users of Xerox's DocuColor printer line, clients can decode their prints using the foundation's Web site by entering the pattern of yellow dots into a grid-based decoder at www.eff.org/privacy/printers/docucolor/index.php#program.
Goodman said much of the paranoia surrounding government intrusion into Internet history or personal library records for subversive-tracking purposes seems unlikely and impractical.