Patent Law Practice Center

What is Prior Art?

Written by Gene Quinn (of IPWatchdog and Practice Center Contributor)

Unfortunately there is no easy answer to the question of prior art, particularly for those who are new to the patent field. We can start off with the understanding that a particular reference or piece of knowledge will be considered to be prior art that must be overcome by a patent applicant if the patent examiner is legally allowed to use it against the applicant to reject one or more claims in a pending application. Likewise, a reference or piece of knowledge will be prior art if it can legally be used to invalidate one or more claims of an issued patent during litigation.

The trouble with explaining what prior art is stems from the fact that everyone already thinks they know what it is. Conceptually we do not want to issue patents for inventions that are not considered new, which seems fair enough. The trouble is defining what is “new.” For now, let’s just say that prior art must be a reference of some type (i.e., a patent or a printed publication) or some type of knowledge or event (i.e., public knowledge, public use or a sale of a product) that demonstrates that the invention in question is not new. (more…)