Of course, some part of a valuable claim is simply avoiding errors by claiming what the invention is not. Claims drafted improperly can cost a client dearly, as was the case in the 2004 Federal Circuit case, Chef America, Inc. v. Lamb-Weston, Inc. Chef America, Inc. accused Lamb-Weston, Inc. of infringing a patent that covered a process for making dough. One of the patent claims required, “heating the resulting batter-coated dough to a temperature in the range of 400 degrees Fahrenheit to 850 degrees Fahrenheit.” Though heating dough to such a temperature would turn it to charcoal, and though Chef America, Inc. insisted that the language meant that the oven (not the dough) was to be heated to such a temperature, the Federal Circuit ruled that Chef America was stuck with what the claim literally recites.
As any patent attorney worth his/her salt will tell you, don’t hang your hat on expecting people to know what you mean. Leave nothing open to claim interpretation – say what you literally mean. If you mean that an oven is to be heated to a temperature in the range of 400 degrees Fahrenheit to 800 degrees Fahrenheit, and then the dough is to be heated in that oven, you had better spell that out in the claims.
The article then addresses common pitfals and what to do about them.