Microsoft Digs In For Another Patent War Of Attrition

But if past WPA-related patent infringement cases are any indication, this legal battle isn't over yet.

In the latest chapter of a case that began back in 2003, a federal court in Rhode Island on Wednesday ruled that Microsoft infringed on a patent belonging to Uniloc, an Irvine-based antipiracy software vendor.

Uniloc's patent pertains to an algorithm that generates a registration number unique to the platform on which data or software is used, and the company claims Microsoft's WPA mechanism for Windows uses this technology in an infringing manner.

WPA works by asking the user to enter a unique code when first launching Windows, and essentially ties the software to a specific machine to block users from installing a single copy on multiple PCs.

Microsoft, as its lawyers have been saying for years, doesn't feel Uniloc's patent is valid. "We are very disappointed in the jury verdict. We believe that we do not infringe, that the patent is invalid and that this award of damages is legally and factually unsupported. We will ask the court to overturn the verdict," a Microsoft spokesperson said in an email.

In 2004, Z4 Technologies, a Michigan-based patent holding firm, sued Microsoft for using its technology in WPA, and in April 2006 won a $115 million judgment against Microsoft in U.S. District Court in Eastern Texas.

Four months later, the judge in the case slapped Microsoft with an additional $25 million in fines for litigation misconduct. After a subsequent Microsoft appeal was denied in November 2007, Z4 sued Microsoft again for not complying with the terms of the ruling quickly enough.