US patent office tweaks rule amid court fight

WASHINGTON, Aug 7 (Reuters) - The U.S. Patent and Trademark Office said on Thursday it would limit the retroactivity of a controversial new rule aimed at reducing the size of patent applications and cutting a backlog of patent requests.

The retroactive features had been one of the objections to the rule that was thrown out by a federal court in April. The patent office has appealed the decision to the U.S. Court of Appeals for the Federal Circuit.

The blocking of the rule was a victory for Europe's biggest drugmaker, GlaxoSmithKline Plc (GSK.L: Quote, Profile, Research, Stock Buzz) (GSK.N: Quote, Profile, Research, Stock Buzz), which had challenged the rules, and other companies with large patent portfolios.

Because the new rules were to be retroactive, companies like Glaxo feared they would have to refile patent applications.

The patent office had argued the limits were needed to reduce a large and growing backlog of applications, which sometimes consist of two dozen boxes of documents.

The patent office said on Thursday that some portions of its rule, if the court injunction were removed, would only apply to applications filed on or after a new, future effective date.

The change would exclude from retroactivity a requirement for applicants to provide a list of related applications and another requirement to explain conflicting applications or why related applications are not claiming the same invention.

A statement from the patent office said it was aware that some applicants may be anticipating a removal of the injunction and it was announcing the change so applicants didn't undertake unnecessary preparation to comply with specific provisions.

Provisions related to the number of claims filed in support of an application would still apply to previously filed applications.

Additional documentation would be required if there are more than 25 claims in support of a patent application. (Reporting by Tim Dobbyn; editing by Carol Bishopric)