“A preamble may limit the claimed invention if it recites additional structure or steps that the specification underscores as important, or if it is clearly relied on during prosecution to distinguish the claimed invention from the prior art.”
Background / Facts: The patent being asserted here relates to a method of allowing a user to selectively rotate a display window in a graphical user interface, e.g., in Microsoft Windows. Despite the importance placed on the “selectively rotating” concept in both the specification and the prosecution history, this phrase is not used in the body of the claims, but rather, only in the preamble.
Issue(s): Whether the preamble term “selectively rotating” is a claim limitation.
Holding(s): Yes. “Because the intrinsic record emphasizes the importance of ‘selectively rotating’ and because the prosecution history shows that the patentee relied on the term ‘selectively rotating’ to distinguish the claimed invention from prior art, the district court correctly determined that ‘selectively rotating’ is a claim limitation.”