The number of times that a patent has been cited by later patents, controlling for such factors as the class of technology and the age of the patent, is widely recognized as one indicator of the relative value of that patent. The methodology is used in intellectual property valuation and in the related academic literature. While results from patent citation analysis have been presented to a jury in at least one patent trial, courts have not ruled directly on its   appropriateness. There have been some Daubert opinions that excluded expert testimony based upon the use of patent citations as indicators of value and of a reasonable royalty, but the courts have criticized errors in the application of the methodology, not the appropriateness of the methodology itself.

In this article from Law360, Dr. Alan Cox and Dr. Nadia Soboleva examine the successful Daubert motion directed against the use of patent citation analysis by the plaintiff’s damages expert in Finjan Inc. v. Blue Coat Systems Inc. They explain that the case provides another example of a courtʼs criticism of errors in application rather than of the methodology itself.