Patent law both imposes a duty on patent applicants to submit relevant prior art to the USPTO and assumes that examiners use this information to determine an application's patentability. In a recently-published paper, Christopher Cotropia, Mark Lemley and Bhaven Sampat tested the validity of these assumptions by studying the use made of applicant-submitted prior art by delving into the actual prosecution process in over a thousand different cases.
In short, the findings are quite disturbing:
We find, to our surprise, that patent examiners effectively ignore almost all applicant-submitted art, relying almost exclusively on prior art they find themselves. This is not simply because the applicant has “drafted around” the art they submitted. Even late-submitted art is ignored by examiners. Either applicants submit uniformly weak prior art, or examiners simply ignore what they receive and focus on the art they find themselves. Based on our further examination of the data, the latter explanation seems more likely.These findings have significant implications on a number of important legal and policy disputes:
(1) Outsourcing patent searches - if examiners only pay attention to the art they find for themselves, the effectiveness of outside submissions may be questionable.
(2) Presumption of validity - should the law presume a patent valid over art that the examiner has not given much consideration?
(3) Inequitable conduct - the findings suggest that the most common form of inequitable conduct - the willful failure to submit prior art to the USPTO - may be less of a problem than previously thought; not because applicants don't try to deceive the USPTO, but because any effort to do so seems wasted.
(4) Patent valuation - "citation counts" are often used as a prominent measure of a patent's strength. If counts become inflated due to repeated submissions by an applicant, the strength (i.e., value) of the patent may become overstated.
Other findings from the study:
- Over three-quarters of the submitted art against which patentability is evaluated comes from applicants. Most of the art (63%) is previous U.S. patents.
- Examiners account for a much larger share of citations to U.S. patents versus other types of art. Examiners account for 34% of citations, versus 6.2% for non-patent art and 6.1% for foreign patents. This is consistent with prior suggestions that patent examiners primarily search prior U.S. patents.
- 17 % of the patents in the sample were issued with no rejections.
- Of the references examiners use to reject claims, only 12.7% come from the applicants, while 87.2% come from examiners.
- Over 90% of the U.S. patents used in rejections emanate from examiner searches, rather than from applicants.
- Examiners used only 2.9% of the applicant-submitted foreign patents and 1.1% of the applicant-submitted non-patent art.