Patent attorneys approach the patent application process with an awareness that the things they say and do on the patent application record will directly impact their clients’ patent rights. In particular, patent attorneys must be mindful of limiting statements and claim amendments they make as such actions may limit the scope of patent protection afford to their client. Courts may limit patent protection under the legal doctrines of “prosecution disclaimer” and “prosecution history estoppel.”
Prosecution disclaimer serves to limit the literal scope of patent protection afforded to a given patent claim. For example, if a patent claim describes a “mobile computer,” the literal meaning of mobile computer could be limited to computers without attached keyboards and displays if prosecution disclaimer applies.
Prosecution disclaimer might apply if the patent attorney extensively distinguished the inventor’s “mobile computer” from laptop computers in the patent application record or the patent application itself. Clients may wish to tout the weight and cost benefits of not having an attached keyboard and/or display, but the patent attorney must counsel the client how this might limit the inventor’s patent protection.
Prosecution History Estoppel
Prosecution history estoppel serves to limit what a court will consider “equivalent” to the inventor’s claimed invention. Courts consider equivalent subject matter to be close enough to what the inventor literally describes to justify protecting the similar subject matter under the patent as well as the literally described subject matter. For example, a court will likely deny protection for a product otherwise similar to the inventor’s claimed invention if the patent attorney argued during the patent application process that the inventor’s invention was different than the similar product.
Thus, patent attorneys and inventors should carefully consider technical details included in patent applications and Office Action amendments when those technical details might serve to limit the inventor’s patent protection. Often times, technical details are necessary and beneficial, but sometimes the patent attorney will recognize that omitting certain details and arguments will best serve the inventor’s interests.