Cursory inconsistencies in terminology—although not ideal—are not a strong enough suggestion that the patentee intended to redefine a well-established term of art, especially when the limitation at issue is not the actual invention itself or an otherwise critical feature. Here, for example, the single use of “Media Access (MAC) address”—dropping the word “Control”—was found to be insufficient to redefine an established term of art with a narrower definition than the traditional MAC address. “For a patentee to act as his own lexicographer and give a term something other than its well-established meaning, he must ‘clearly set forth a definition of the disputed term.’” It may nevertheless be best to use consistent terminology when a consistent meaning is intended.
Background / Facts: The patent being asserted here is directed to a network for wireless communications between a central hub device and a number of surrounding peripheral devices in close proximity with the hub device. In this regard, the claims recite that the hub device orchestrates all communication in the network using a plurality of “MAC addresses” identifying the peripheral devices. The parties agree that, at the time of invention, the conventional meaning of “MAC address,” i.e., a Media or Medium Access Control address, was that it operated to uniquely identify a wireless device and could be generated in two ways—by the manufacturer of the device or by the local network.
Issue(s): Whether the patentee acted as his own lexicographer by redefining the claimed “MAC address” to refer only to a local address generated by the hub, even though the ordinary and customary meaning included either local or universal MAC addresses.
Holding(s): No. “Through the single, cursory use of ‘Media Access (MAC) address’—dropping the word ‘Control’—the specification did not re-coin an established term of art by redefining it to have a narrower definition than the traditional MAC address. Dropping the word ‘Control’ was not unknown to those of ordinary skill in the art, based on other technical literature. … This one indicium therefore is simply not a strong enough suggestion that the inventor intended to displace a well-established term of art.” Further, “[a]lthough there is no specific reference to universally generated MAC addresses in the specification, using a term the same way in all disclosed embodiments is not by itself sufficient to redefine a term of art. … The specification does not state that a hub-generated MAC address is the actual invention itself or that hub-generation is a critical feature. … Moreover, nothing in the specification or the prosecution history shows an attempt to distinguish over prior art for lacking a hub-generated MAC address.”