It's a simple fact that the United States Patent and Trademark Office (the "USPTO") is inundated with patent applications. Given the sheer volume of applications, patent examiners can only spend a limited amount of time examining those applications. Further, given the fact that an applicant for a patent does not have to conduct a "prior art" search before filing, it is virtually impossible for an examiner to turn up all of the prior art that is relevant to a patent application.
Unbeknownst to many patent practitioners, however, the USPTO is getting ready to wrap up a yearlong pilot project directed at giving the examiners a little help in turning up prior art.
Last year the USPTO, in conjunction with the New York Law School, launched a program titled "Peer to Patent." This pilot project enables the public to comment on and submit prior art that may be relevant to pending patent applications. The project is somewhat limited in scope as only patent applications that relate to computer architecture, software, and information security are eligible for this process and applicants must agree to submit their patent applications to this process. However, preliminary numbers reported by the organization indicate that the project may be an effective means of reviewing patent applications.
According to the "Peer to Patent" Web site, over 2,000 people have signed up to participate as reviewers of patent applications and have submitted 192 pieces of prior art on 42 patent applications.
For more information about the process, see the USPTO's description of the program here.