Last November, the Federal Circuit panel opinion in Williamson v. Citrix held that the district court erroneously construed the limitation "distributed learning control module" as a means-plus-function expression. The majority emphasized that failure to use the word "means" in a claim limitation creates a strong rebuttable presumption that it is not a means-plus-function limitation. In dissent, Judge Reyna argued that the limitation simply substituted the "nonce" word "module" for "means." On December 5 (exactly six months ago), Citrix et al. filed for rehearing en banc, supported by amicus briefs by the EFF and a group of IP professors (including me). The IP professor brief, written by Mark Lemley, argues that patentees have exploited the Federal Circuit's inconsistency in this area to engage in functional claiming without satisfying means-plus-function claim rules.
Based on the timelines in the Federal Circuit's internal operating procedures, it seems improbable that the court could still be deciding whether to act on the rehearing petition. So perhaps the court granted rehearing en banc without argument? Issuing an en banc decision can take a while—Akamai v. Limelight took over 9 months from argument to opinion—but that was unusual, so maybe we will hear something soon. (Here is the Williamson v. Citrix docket on Bloomberg Law, subscription required.)