Patent reform was supposed to make patent litigation less common, and less costly. But it could wind up costing Versata Software Inc. a whopping $391 million, if SAP America Inc. and its lawyers at Finnegan, Henderson, Farabow, Garrett & Dunner get their way.

On Sunday SAP petitioned the U.S. Patent and Trademark Office to review a Versata patent that SAP was found to have infringed by a jury last year, in one of the biggest patent showdowns of 2011. The filing makes SAP among the first to take advantage of new post-grant review provisions of the America Invents Act that took effect the same day — exactly one year after President Obama signed the AIA into law. The new rules allow anyone charged with infringement of a business method patent to request that the USPTO cancel one or more of the patent’s claims. Other types of patents will be eligible for post grant review after the final phase of the AIA is implemented next March.