Prosecution Data

This morning, I pulled up 10,000 of the most recent patents to see what’s going on with pendency and other issues.

Pendency: About 65% of the patents were original applications (i.e., not based on a prior US filing).  The original applications issued after an average of 40.4 months delay (3 years, 4 months).*  The remaining 35% represented continuations, CIP’s, and applications based on prior provisional filings.  Those non-original applications had a pendency of just under 3 years (35.3 months).** The shortest original application pendency was 4 months (No. 7,172,439) and the longest stretched for over 13 years (No. 7,169,572).***  Chart I below shows the histogram of pendency for the whole group in 6-month buckets.

Examiner: About 63% of the applications were examined by an Assistant Examiner.  On average, the patented cases for assistant examiners took about four-months longer than examined only by a Primary Examiner.****

Foreign Priority: Unlike US Priority, a patent that claimed foreign priority did not seem to alter the expected time to issuance. About 41% of applications claim priority to a foreign patent document.  The biggest foreign locale was Japan.

Citations to Prior Art: As the PTO has reported, most patents cite fewer than 20 references. In our sample of 10,000 patents, the median number of citations was 13-14. The average number citations, however, was over 25.  That skewed average comes from a small number of patents that include a very large number of citations. Six patents issued to Shell (or a Shell shell) each cited over 1000 references and may have presented the entire history of oil drilling dating back to the 19th century. (See, No. 7,172,019). 15% of applications included 40 or more citations while 20% included 6 or fewer. The majority (64%) of the cited references were to US Patent Documents and over half of the patents cited no non-patent prior art.

Claimset Length: I also wanted to see whether longer claimsets increased the length of prosecution — they do.  Chart II below shows pendency as a function of claimset size percentile.***** This statistic is a bit odd because it is based on the number of characters in a claimset, but the character count appears to be a fairly-good single-variable proxy for the length and complexity of a claimset.

Technology Class: The greatest predictor of pendency is likely the technology classification. There are likely two primary factors driving the measured difference between technology areas: (1) Backlog; and (2) Heightened Scrutiny. Some art units have large backlogs of patent applications waiting to be examined while others have much smaller dockets.  Since patents are examined roughly in order, a longer backlog results in longer pendency. In addition, some of those same units with large backlogs are also the ones who have instituted the second-pair-of-eyes review to ensure that the patents that issue should be issuing. This heightened scrutiny is expected to increase pendency as well. Table I shows a handful of classes and their average pendencies.

Recently issued Business Method patents (Class 705) took over five years to issue, and DNA-type patents (Class 435) were over four years.

Inventorship: Most patents list only one or two inventors. This is reflected in Chart III below. The number of inventors did not prove to have a significant impact on pendency.  One patent did list 25 separate inventors. (No. 7,169,760). That patent was, however, quite far from the mean number of inventors calculated at 2.5.



  • Cite as Dennis Crouch, Prosecution Data, Patently-O (February 15, 2007),
  • * 95% CI 49.96 – 40.83 months.
  • ** 95% CI 34.7 – 35.9 months. T-test shows difference between two sample averages at p<0.001. As can be seen from Chart I, the data is not exactly normal, but it is somewhat close. A more particular test would also factor in the skewed nature of the data.
  • *** I excluded No. 7,177,516, which was filed over 19 years ago because it was held under a secrecy order.
  • **** Average pendency for cases with assistant examiner was 41.4 months while the average pendency for cases signed only by a primary was 37.0 months. The difference between these averages is significant at p<0.001 using a t-test.
  • ***** Error bars are shown at the 95% CI.

27 thoughts on “Prosecution Data

  1. I think these stats are a great job! I would like to see correlation by class (specifically 060/775 if possible)

    a) Does anyone know if there is any way to appeal Pettition to make special decisions?

    b) Is this new “12 month decision” process going to derail? Will it negatively affect pending applications (i.e. give the low hanging fruit priority) if you look at USPTO metrics what is the incentive for them to care about existing patents rather than focus on the ones that get their pendency numbers down (i.e. 12 month accelerated plan)

  2. Very interesting, indeed. Similar observations have been made in Europe and a deep analysis of the surge in patent applications size (claims and pages) and on its underlying drivers and consequences on the European Patent System is presented in two papers, available at link to and link to respectively. These results show that the average size of applications at the European Patent Office has doubled over the past two decades and that it is strongly influenced by the increasing recourse to the PCT option, US drafting styles and technological areas (especially biotechnologies). This increasing size (or voluminosity) of applications has a strong impact on EPO’s workload and processing efficiency, justifying the need for regulatory action. Evidence from recent changes in US patent fee policy is shown to have a significant knock-off effect on voluminosity indicators for second filings at the EPO.

  3. Come to think of it… Other stats might benefit from comparing by class as well. Another example is Assitant Examiner vs Primary Examiner pendency. Many of the new business class art units are necessarily populated by junior examiners and have high pendency rates. Adjusting by class would do much to acount for these errors and give a more accurate picture of the difference in time by examiner type.


  4. It might be worth considering running your data again with regards to claim characters (volume). Specifically, you might consider seeing if correlation exist inside the same class as claim volume increases. By measuring just claim length, you might just be seeing a correlation between pendency and class (i.e. class 705 having more and longer claims than class 33).

    Of course, you might have to increase your sample size, but the results would certainly be more informative.


  5. I don’t mean to sound ungrateful for the great work done in gathering these statistics but is there some way to see if patents are issued more easily to big companies (e.g. IBM, Microsoft, Shell) at the expense of small companies and start-ups?

    I have heard enough rumors that the USPTO issues endless numbers of unbased/unfair/silly rejections, bizarre election requirements and continuous changes of Examiners all with the intent of drying up a small company’s funds.

    On a different note, DS says “Pre-appeal conferences or appeal conferences are set up to prevent bad rejections from reaching the board. They are to be stopped within the TCs. Pre-appeals are better for the applicants, as they would tend to avoid the rather large expenditure of filing a brief to overcome a shoddy rejection.”

    Has any one ever had success with the pre-appeal conferences where a silly rejection has been overturned? My experience is that these are primarily a way to waste another few months before you go and file the actual appeal.

  6. Dennis: You put together a table of the average backlog of patent applications by Technology Center (2005). I faithfully kept a copy. I have also searched the USPTO site and not found similar (updated) statistics. Where should I be looking? (I am aware of the “predication” of first office action available through private PAIR.) Thanks

  7. Regarding class 705 patents: The patents issuing today were filed in the good old days (e.g. pre 2001) when it was only a year or two before you got a first office action. Delays to first office action for patents filed today in this class are now projected at 4+ years. Add to that 3- 5 years active prosecution time and you can see that the current pendancy numbers underestimate the true magnitude of the problem.

  8. I think maybe some of you are confusing 2nd pair of eyes with either appeal conferences, or the newly instituted pre-appeal conferences. 2nd pair is just a cursory look at a newly allowed case to see if something glaring pops out that should be looked at closer (an allowed 2 line claim or a continuation where the parent needs to be checked for ODP comes to mind, for example). None of this would have any bearing on the BPAI, since they only see rejections, and they don’t generally care where the rejection comes from once they get it.

    Pre-appeal conferences or appeal conferences are set up to prevent bad rejections from reaching the board. They are to be stopped within the TCs. Pre-appeals are better for the applicants, as they would tend to avoid the rather large expenditure of filing a brief to overcome a shoddy rejection.

    Now, as for pendency numbers, one thing I’m not hearing about, unless it’s buried somewhere in all that text above ;), is the increasing number of applications over the past few years which are difficult to properly classify. Claims, even seemingly simple ones, can be hard to assign, since they are written in a way which could place them in a variety of locations within the PTO. Sometimes, they will ping pong around for years before they are docketed to a specific examiner. So, before we even get to interpretive claim analysis and stretched references, we may be well past the point of no return on the applicant’s investment.

  9. Alan asks: “With the route to the Board effectively cut off by the “second pairs of eyes,”… ”

    I have to admit I don’t understand this line. How is an appeal stopped by the “second pair of eyes”? The prosecution may well be delayed, but once you get a final rejection what can stop your appeal?”

    Alan, reviewers (second eyeballs) never give in and tell the examiner to allow the application. So, even after final rejection, after appeal, after writing and filing a brief, the examiner is instructed to re-open prosecution. This can be done ad infinitum. I have personally written four briefs in one case where the examiner re-opened after each one. I finally called the SPE and told them to cut it out. That particular one finally went through to the Board and was eventually allowed.

  10. Mark Lemley: “It is worth noting that these pendency statistics substantially understate the average time to issue, because the stats Dennis gives us are only pendency of the instant application.”

    DDC: Excellent point. I suspect that the average will be well over 4 years — quite an increase. I should be able to extract that data from the doucments that I have here. Also, you are right that, for this data, an RCE is not considered a continuation.

  11. “With the route to the Board effectively cut off by the “second pairs of eyes,”… ”

    I have to admit I don’t understand this line. How is an appeal stopped by the “second pair of eyes”? The prosecution may well be delayed, but once you get a final rejection what can stop your appeal?

    Is your point that the Board is more hesitant to reverse a rejection where there has been a “second pair of eyes” examination? In my opinion, just like the CAFC thinks it knows how to interpret claims best and has no problem reversing, the Board thinks it knows patentability best and will affirm or reverse as it sees fit.

  12. A pendancy of 61 months for class 705 begs the question of the real value of software and business method patents. The average shelf life of software used to be about 2-3 years. I think it must be shorter now. With 61 months of pendancy in class 705 this creates an economic absurdity. By the time a patent in 705 issues, technology has moved on. While there is the possiblity of infringement damages back to publication date, many patents in this class won’t be pursued in the PCT, and so inventors chose to avoid publication. How do we advise clients of the value of patent protection with such long pendancy? Any ideas?

  13. Sorry Gary, I did not mean to come off as a smart-alic to you personally. I’m so bitter about that area of the PTO. I’ve seen many of these types of applications abandoned because of lack of funds or other financial considerations. All the while, we face numerous rejections without proper factual basis. With the route to the Board effectively cut off by the “second pairs of eyes,” prosecution costs rise, with little or no results. It amounts to a big bowl into which we throw money (with that familiar swirling sound).

    I feel guilty. We get paid, but the inventors/applicants get screwed. Meanwhile, examiners receiving these abaondonments think they are “successful,” thus reinforcing their bad behavior. It is so crazy now, something’s got to give.

  14. It is worth noting that these pendency statistics substantially understate the average time to issue, because the stats Dennis gives us are only pendency of the instant application. If you calculate total time from first filing to issue, it looks like the average will be over 4 years (up from 2.77 years in 1996-1998, based on data John Allison and I put together).

    Also notable is the fact that continuations are barely any faster than original apps. I assume these are statutory continuations, not RCEs?

  15. Thanks, JohnG, Your answer is comforting… I thought the dependency is infinite PLUS 2 months.

    Thanks, Jason, I can see it.

    My real question is, the dependency statistics is for the filings ( class 705) about five years ago. Does anyone have a guess the dependency of a current filing?

  16. Kurt Leyendecker:

    “Crazy you say…. Crazy like a fox!

    Check out Peter Zura’s take on the CAFC Cargill v. Cambra Foods decision. link to

    Disclose, Disclose, Disclose OR risk having you patent declared in on the basis of inequitable conduct.”

    I wish it was that easy. You can be accused of inequitable conduct for “burying” a reference too.

  17. Thanks Dennis. Now I have hard numbers to show inventors when they ask how long it is going to take. Much better than my standard response of “a really, really long time.”

  18. Dennis: Thanks for your efforts. One point to be made, regarding the relationship between longer claimsets and the length of prosecution. The former does not necessarily cause the latter. That is, the dropping of rejections in favor of new grounds generate longer claimsets. In attempts to respond to examiner interpretations of claims and/or prior art, in addition to traversing the rejections, applicants present alternately worded claims in addition to those previously presented. Of course, when rejections are withdrawn in favor of new grounds, the number of claim then increases.

  19. I assume by “Business Model Patents” you mean business method patents which would fall under classification 705. They have an average pendency of 61.1 months in the chart cited above.

  20. I concur with JohnG’s comment. Fantastic job Dennis. You just did this in a morning? You started at 12:01 AM? Thank you very much for the data!


  21. Thanks so much for putting these stats together. You did all this today? Wow.

    Gary: Infinity minus two months.

  22. Did you see the cross-reference to related applications section on that Shell patent? Four screenfulls! (text, not pdf)

  23. Dennis:

    Your stat on continuations, divisionals, etc. having a shorter pendency makes some sense, particularly when you consider that on the one hand the Examiner is familiar with the case and needs less “getting up to speed” time, and on the other hand some of these claims will be more difficult to get (broader, etc.) which is why they are continuations in the first place (but this may not impact divisionals).

    Easy to see why the examining corps wasn’t crazy about the continuation proposals of a year ago.

    Nice work.

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