The Federal Circuit's opinion in American Chef v. Lamb-Weston is a favorite of mine for illustrating the tricky business of patent valuation. At issue in the case is the proper interpretation of a claim limitation that requires "...heating the dough to a temperature...." The patentee asked the court to apply a claim interpretation that essentially changed the word "to" to "at". The patentee wanted the claim to read "...heating the dough at a temperature..." because heating dough to the specific temperature range recited in the claim would burn it to a crisp. The defendent, for obvious reasons, was not performing such a heating step.
As a claim interpretation case, American Chef is not necessarily suprising. So, what does the case have to do with patent valuation? It's a reminder that, as with cooking, timing is critical.
When the opinion issued in 2004, it had the potential to limit the scope of any issued patent claim that includes a "heating to..." step. While each patent is its own universe and a full legal analysis is necessary to determine whether a claim does or does not read on a particular product or process, decisions like American Chef lurk in the legal texts awaiting unsuspecting patent claims.
Most importantly, though, these decisions can be handed down at any time and have the potential to impact the scope of the claims in any issued patent. American Chef reminds us that the law of claim interpretation, and thus patent valuation, changes frequently. At its best, the legal component of a valuation analysis is a snapshot of the value of a patent. It represents a single point in a time continuum. Ideally, for important patent valuations, you should watch the whole movie, or at least flip through several snapshots. The analysis should be treated as fungible, and should be updated as appropriate.
Image: Frau beim Brotbacken (Woman Baking Bread) by Jean-François Millet (1854) (public domain)