Williamson v. Citrix Online, LLC

Richard Williamson (plaintiff) held a patent on a virtual-classroom system; Claim 8 recited a distributed learning control module for receiving, transmitting, relaying, and coordinating communications on a special-purpose computer. Williamson sued Citrix Online (defendant) for infringement. Citrix argued the claim was indefinite under 35 U.S.C. section 112. The district court held that the module term was a means-plus-function limitation under section 112, paragraph 6, and that Claim 8 and its dependents were invalid. Williamson appealed.

Whether a claim limitation that recites a function without a sufficiently definite structure is a means-plus-function term that is indefinite when the specification discloses no corresponding structure.