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The USPTO published the most recent statistics on inter-partes and ex-parte reexaminations, and both reports show that reexaminations continue to grow in popularity, and continue to be effective weapons for challenging validity.

Ex-Parte Reexamination

Ex-parte filings continue to grow - 2009 is on pace to almost double the number of filings from 5 years ago:

2002 - 274 filings
2003 - 392 filings
2004 - 441 filings
2005 - 524 filings
2006 - 511 filings
2007 - 643 filings
2008 - 680 filings
2009 - 481 filings (through 6/09)

Of these filings, 31% are known to be in litigation. Just as before, reexamination requests are overwhelmingly granted - currently 92% of requests are pushed forward towards full reexamination proceedings. On pendency, ex parte reexamination requests have an average pendency of 25.1 months, and a median pendency of 19.1 months.

Requesters continue to be favored during reexamination. Of all requests, only 25% of reexamined patents emerge with a certificate having all claims confirmed. 64% of reexamined patents emerge with claim changes, and 11% emerge with all claims canceled.

Inter-Partes Reexamination

Inter-partes reexamination requests continue to grow at a much higher pace - the number of requests through June 2009 already exceed the total number of requests from the previous year:

2004 - 27 filings
2005 - 59 filings
2006 - 70 filings
2007 - 126 filings
2008 - 168 filings
2009 - 195 filings (through 6/09)

Of these requests, 66% of the challenged pates are known to be in litigation. Currently 95% of inter-partes requests are granted. On the pendency side, the news is not good. Currently, the USPTO claims an average pendency of 36.1 months, and a median of 33.o months. This is up from December 2008, where the average and median pendencies were 34.9 and 32.5 months respectively. It is worth noting that an earlier study by the Institute for Progess found that actual pendencies for inter partes reexaminations are closer to 43.5 months, and may be high as 97 months (!) (link).

Requester success rates are now higher than ever - only 5% of challenged patents emerge with all claims confirmed. 35% of challenged patents emerge with claim changes, and 60% of challenged patents have all claims canceled or disclaimed. In December 2008, 9% of the challenged patents had all claims confirmed, with 21% having claim changes and 70% having all claims canceled or disclaimed.


- Download USPTO, Inter Partes Reexamination Filing Data - June 30, 2009

- Download USPTO, Ex Parte Reexamination Filing Data - June 30, 2009
- See also Reexamination operational statistics - FY 2009 (through 6/30/2009)