Extreme citing behaviors in patents: When the duty of candor backfires

This paper analyses extreme citers: patents that cite an extremely high number of references to prior art. We find that around 17,000 patents, 0.04% of the total, contribute over 20 million references, 5% of the total. Extreme citers are a relatively new phenomenon, but they are becoming increasingly popular. They seem to be coming from a few applicants, notably Ethicon and Apple. We recommend researchers to carefully consider citations from extreme citers in their patent citation analyses.