Several months ago, letters started going out to small and medium-sized businesses around America suggesting that they will be targeted by a "scan to e-mail" patent lawsuit—unless they buy a license at a cost of around $1,000 per worker. The letters have gone out from 40 different shell companies with names like AdzPro, IntPar, and GosNel, and they're all controlled by MPHJ Technology Investments, a mysterious patent-holding company whose owner, or owners, are being kept anonymous by the lawyers who work for MPHJ.

The inventor named on the patents, Laurence Klein, resides in Israel and has a murky connection with the current patent holder. MPHJ head lawyer Brian Farney insists Klein was a pioneer. "No one had a system where you did these things—where a scanner, a LAN, a PC, and the application software [were linked] with automatic or one-button scan,” Farney told Ars.

Pioneering patents or not, last week, MPHJ came under attack from many directions. First, there was the unprecedented lawsuit launched last week by the Vermont attorney general, William Sorrell, claiming that MPHJ's letters are misleading and violate state consumer-protection laws. (Sorrell says that MPHJ has no particular evidence that the companies it targets are actually making use of the technology.) At about the same time, scanner makers Xerox and Ricoh challenged one of the patents by filing an "inter partes review" at the US Patent and Trademark Office.

Ars has now learned that HP has also filed a petition (PDF) challenging an earlier-issued MPHJ patent, No. 6,771,381. The patent describes a "virtual copier" that "involves paper being scanned from a device at one location and copied to a device at another location."

In the petition, HP says its own printers, the ScanJet 5 and LaserJet 3100 (circa 1997) and the ScanJet 4Si (circa 1995), had all the functionality described in the patent. It also mentions other patents that anticipate the '381 patent's claims. The petition includes manuals for the printers, which describe how to scan documents to e-mail a year or more before Laurence Klein's patents were filed.

HP's petition was filed on May 24, one day after Xerox and Ricoh filed their own petition (PDF) focusing on networking technology. The patent being critiqued in that petition "claim[s] nothing more than a well-known concept for enabling a typical PC user to add electronic paper processing to their existing business process," Xerox lawyers state. Xerox's own networking systems predate the MPHJ patents by a full decade, the petition argues.

An HP spokesperson declined to say anything about the petition or about why the company chose to fight this particular MPHJ patent. Patent office records don't show any legal challenges against the two other MPHJ patents not subject to last week's petitions.

New rules stemming from the America Invents Act have strengthened the legal process being used by HP, Xerox, and Ricoh. It's known as "inter partes review," which replaces "inter partes reexamination." Essentially, the review allows a party to argue to the Patent Office that a patent shouldn't have been issued in the first place. Under the new process, if the petition for review is accepted, a determination must be made within one year (or 1.5 years if an extension is granted). That's considerably faster than federal court litigation—and faster than the old reexam process, which sometimes dragged on for years.