Although not clearly defined, the backlog of unexamined patent applications consists, at one point in time, of all the patent applications that have been filed and still remain to be examined. The backlog was said to be 4.2 million worldwide in 2007, and in 2009 it reportedly continued to grow. Alone, the United States Patent and Trademark Office (USPTO) was reported to have, in 2009, a backlog of more than 700,000 patent applications. According to Beth Simone Noveck,
The backlog has reached Borgesian proportions, and it feeds on itself: The patent examiner has less time to review more applications. Reviews become less rigorous. The easier the application process becomes, the more inventors apply.
According to Alison Brimelow, former president of the European Patent Office, the "backlog of patent applications is counter-productive to legal certainty, and that has a negative effect on the innovation process". According to a 2010 study by London Economics, "the cost to the global economy of the delay in processing patent applications may be as much as £7.65 billion each year."
According to former U.S. federal judge Paul R. Michel, in an interview conducted in 2011, "delay is [...] the greatest problem with the [U.S.] patent system" and "[the USPTO] desperately needs thousands of additional examiners and new IT systems. Indeed, it has needed them for years."
Since 2006, a number of collaborations, known as Patent Prosecution Highway (PPH), have been set up between various patent offices, in order to avoid the duplication of search and examination work and ultimately reducing the patent backlog.
- Economic Study on Patent Backlogs and a System of Mutual Recognition, Final Report, To the Intellectual Property Office Prepared by London Economics, January 2010 (pdf, 1,59 MB).
- Global Symposium for Intellectual Property Authorities, PCT Newsletter, October 2009, p. 2.
- Amy Schatz, New Chief of Patent Office Takes Aim at a Massive Backlog, The Wall Street Journal (Online), October 10, 2009. Consulted on October 10, 2009.
- Beth Simone Noveck. Wiki Government: How Technology can Make Government Better, Democracy Stronger, and Citizens More Powerful. Washington, D.C.: Brookings Institution Press, 2009, p. 59.
- Kaitlin Mara, Brimelow Stresses Need For Better Patent System; Discusses Harmonisation, Intellectual Property Watch, 17 September 2009. Consulted on October 17, 2009.
- UK and US announce action plan to reduce global patent backlogs, UKIPO, Press releases 2010, 10 March 2010. Consulted on April 18, 2010.
- Interview With Chief Judge Paul R. Michel On US Patent Reform, Intellectual Property Watch, July 19, 2011. Consulted on August 8, 2011.
- "Patent Backlogs" UK Intellectual Property Office. Accessed 12 February 2018.
- "Decision T 2707/16 (Dynamically generating multiple hierarchies/MICROSOFT TECHNOLOGY LICENSING) of 11.12.2018" (PDF). Boards of Appeal of the European Patent Office. Reasons 16 to 36. - discussing the length of examination proceedings