In what a company spokeswoman calls a “purely defensive measure,” Amazon.com has filed a lawsuit against Cendent and its subsidiaries, including Orbitz, Avis, and Budget. According to a CNET News report by Paul Festa, “Cendant had sued Amazon for patent infringement in November. Following unsuccessful settlement negotiations, the company refiled its suit in June. Amazon subsequently filed its countersuit.” Festa observes that “Amazon has walked a fine line between decrying the state of software and business process patent litigiousness and building its own healthy patent portfolio. Amazon CEO Jeff Bezos has advocated patent reform for years.” The patents in question include “U.S. Patent No. 5,715,399: secure method and system for communicating a list of credit card numbers over a nonsecure network” and “No. 6,029,141: Internet-based customer referral system.”