Is the Patent Office a Rubber Stamp


  • Mark Lemley
Publish Date:
July 7, 2007
Publication Title:
Stanford Public Law Working Paper No. 999098 .
Working Paper
  • Mark A. Lemley & Bhaven N. Sampat, Is the Patent Office a Rubber Stamp, Stanford Public Law Working Paper No. 999098 (2007).


A growing chorus of voices is sounding a common refrain – the U.S. Patent and Trademark Office (PTO) is issuing far too many bad patents. These criticisms are complicated by the rather surprising fact that we don't actually know what percentage of patent applications actually issue as patents. In this paper, we use a novel dataset of all published patent applications filed in January 2001 to estimate the grant rate. These data also allow us to examine the uses of continuation applications, and to assess dynamics of applicant-examiner interaction over the patent prosecution process. We find that the PTO rejects a surprisingly high percentage of patents. While more than two-thirds of all applications result in at least one patent, a significant number of applications are rejected and then finally abandoned by the applicant. We also find that the likelihood of obtaining a patent varies significantly by industry, but in surprising ways. Finally, despite a variety of reforms that might be thought to reduce the use and abuse of continuation applications, we find a high use of continuation applications of various types.