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How long do patents last? The debate continues

James Nurton

Following our recent post on patent term, WIPO’s chief economist has done some digging – with interesting results

A couple of weeks ago I wrote a post responding to Reuven Brenner’s blog on patent term in the Wall Street Journal. In that, I mentioned the difficulty of finding recent, accurate data on how long patents are maintained on average.

I’m pleased to say I received an email from Carsten Fink, chief economist at WIPO, last week. He said that he and his colleague Hao Zhou have looked into this further. They’ve come up with some interesting thoughts though of course these are preliminary estimates and not detailed research (they are economists after all).

WIPO compiles an annual statistical survey, and as part of this asks IP offices for the number of patents in force and a breakdown of this figure by application year of the patent. Using these data and the assumption that 70% of patent applications are eventually granted (which is probably a high-end estimate), it’s possible to calculate the share of granted patents applied for in a given year that are still in force.

The problem of course is that this distribution is truncated to the right – only a small share of patents applied for in recent years are in force as only a few of them have been granted.

Year Average life (years)
2004 13.7
2005 13.8
2006 14
2007 14.2
2008 14.2
2009 14.3
2010 13.7
2011 13.6
Average 13.9
However, you can assume that nearly all patents applied for in the previous year are hypothetically in force (otherwise the applicants wouldn’t have applied for them). Again assuming that 70% of patents will eventually be granted and using average pendency information, you can estimate the proportion of pending patents that are hypothetically in force in recent years and add them to the patents actually in force.

Anyway, Carsten and Hao crunched the numbers from 22 offices going back to 2004 to give the average patent life as the weighted number of lags among all patents in force, where the weights are precisely these shares.

The results are shown in the table.

Contrary to what I suggested in my original blog, these figures actually suggest that the average life of patents has remained relatively stable over the past 10 years. Carsten points out there was a noticeable fall in the average life of patents from 2009 to 2010, which is consistent with (at least anecdotal) evidence that tighter IP budgets caused by the global financial crisis prompted companies to cut down on renewals.

However, he also reiterates that this is very preliminary research. Positively, he adds that our interest has prompted WIPO to consider including this sort of information in future editions of the World IP Report, as well as how average life differs between countries and sectors.

I think this would be very valuable. I’d also be interested to know if these rough-and-ready figures tally with the experience of patent attorneys and lawyers.


Article Comments

Thanks for your comment. It begs the important question of what constitutes "use" of a patent: does licensing/cross-licensing? use in negotiations/defensively? assertion in litigation? Depending on the definition, this could be very difficult to answer!

James Nurton May 13, 2013

I think the question should be " How many patents are put to use" instead of "how long do patents last?". I presume that WIPO team has worked out the report on the basis of the maintenace fee paid by the patentee to their respective IP offices. The firms owning the patents have a tendency to create a portfolio of numerous patents to conseal the real meaningful one or to say that these firms create a MIRAGE of patents. So to sustain this MIRAGE, the maintenance fee is paid to IP Offices and the real spirit behind the original question " how long do patents last?" is lost. For an end-user, it is the life of a used patent which matters rather the life of other patents which were created to put a concrete wall to protect the used patent. To get an answer to the posed alternate question, WIPO team has to put lot of resources.

v k bali May 11, 2013

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