Amazon late last month filed the claims in the U.S. District Court for the Western District of Washington, alleging that Cendant and subsidiaries Orbitz, Avis, Budget and Trilegiant infringed four patents held by Amazon.
Cendantfor patent infringement in November. Following unsuccessful settlement negotiations, the company refiled its suit in June. Amazon subsequently filed its countersuit.
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.
Amazon said its current patent action came only in self-defense.
"The suit was filed in direct response to Cendant's refiling of their patent infringement suit," said Amazon spokeswoman Patty Smith. "This is the first time that we have asserted any of these four patents, and we would not have asserted them if Cendant had not filed against us. It's purely a defensive measure."
Cendant did not immediately return calls seeking comment.
The four patents in question are U.S. Patent No. 5,715,399: secure method and system for communicating a list of credit card numbers over a nonsecure network; No. 6,029,141: Internet-based customer referral system; No. 6,625,609: method and system for navigating within a body of data using one of a number of alternative browse graphs; and No. 6,629,079: method and system for electronic commerce using multiple roles.