How Many Patents Make a “Patent War”?

Adam Mossoff —  19 November 2012

I have a guest blog posting up on Intellectual Ventures’ blog on why a patent war — or “patent thicket” in scholarly parlance — cannot be defined solely in terms of the number of patents involved in the legal and commercial conflict. 

 Check it out at:

As an aside, this issue is important because I keep hearing from some quarters that historical patent wars, such as the Sewing Machine War of the 1850s, weren’t patent thickets for precisely this reason; that is, relative to the number of patents involved in the “smart phone war” today, there were simply too few patents involved in these earlier legal conflicts for them to be identified as “patent thickets.” 

For instance, Professor Mark Lemley made this point in a comment to my recent blog post, Today’s Software Patents Look a Lot Like Early Pharma Patents.  Although this short blog posting addressed only how software patents and early pharma patents were both accused by famous judges of being too complex or too vague for the courts to handle efficiently, Mark instead decided to make the tangential comment: “Um, except for the part where there were 250,000 pharmaceutical patents covering the same product.”  (This was made on Facebook, and so, sorry, no link.)

Pofessor Michael Risch has a great blog posting on why the oft-repeated claim that there are 250,000 patents covering each smart phone is overblown, especially as this statistic is used in the increasingly overheated rhetoric in today’s policy debates in which many people are treating as settled fact that there is a so-called “software patent problem.”  

But even if Professor Risch is wrong and there are in fact 250,000 patents covering each smart phone, this would still not justify the claim that the number of patents is the primary cause of today’s patent war. 

I often heard this point from my fellow academics when I was researching my article on the Sewing Machine War of the 1850s — that things are somehow different today because there are lots more patents covering the same commercial product — and thus I specifically address this issue in my paper.  In fact, I spent several pages discussing this issue and why the premise “thousands of patents = patent war” is profoundly mistaken. 

Given the prevalence of the “250,000 patents cover each smartphone” and similar claims today, though, I realize that it’s an important enough point to carve out these several pages and reproduce them in a blog posting (so that people don’t have to sift through a 50-page article to find it).

So, as I said, check out my guest blog posting at IV’s blog, and poke around there a bit to learn more about the cool things that IV is doing with the patented innovation that it creates, acquires and licenses.

5 responses to How Many Patents Make a “Patent War”?


    The ridiculous state of IP law is the main contributor to the patent war. Instead of competing on merit, quality or even price, companies are now “patenting around” truly innovative companies. If the innovators want to carry on with their work, they have to give a slice of the pie they created to the guys/gals who created a fence of patents around them. This is, and will dramatically continue to stifle innovation.

    NTP, a patent troll, was a huge contributor to the demise of RIM. Although RIM had operational problems, NTP’s $625 million injunctive relief settlement with them surely threw an over-sized spanner in the works. IP is important and is a key aspect to incentivizing innovation. Nevertheless, because of the pathetic state of IP law, the exact reverse is now happening.


    Dear Erik – Thanks for the comment, and while you’re correct that, in recent years, commentators have shifted in the variables they use to define a “patent thicket” — similar to the shifts that have repeatedly occurred in the definition of “patent troll” — it’s simply untrue that not a lot of scholars have argued that the number of patents is sufficient for a “patent thicket” to exist. In fact, Carl Shapiro, the professor who first coined this term made exactly this claim in his now-classic article: “Navigating the Patent Thicket: Cross Licenses, Patent Pools and Standard-Setting,” Innovation Policy and the Economy, vol. 1, Adam B. Jaffe, Josh Lerner & Scott Stern eds. (MIT Press, 2001): 119-26. Here, Carl defines a “patent thicket” as “a dense web of overlapping intellectual property rights that a company must hack its way through in order to actually commercialize new technology.” Note that the definition is solely in terms of the number of patents, and there’s no mention of patent quality or vagueness of boundaries (terms that, by the way, have much force as rhetoric but about which the actual empirics have been lacking or at the very least are heavily disputed). This definition and Carl’s article continue to be cited as the definition of “patent thickets” both in academic scholarship and in the public policy debates, Mark’s comment is just one of many examples of this, which is why I was required to spend three pages on this claim in my own article on the Sewing Machine War.


      In the abstract of the very paper you cite, Shapiro defines a patent thicket as “an overlapping set of patent rights requiring those that seek to commercialize new technologies obtain licenses from multiple patentees,” which does not emphasize the involvement of a large number of patents. It could be just two patents, for example. The issue does not arise simply because the number of patents is large (although this may certainly exacerbate the problem). Indeed, a complicated piece of manufacturing equipment may involve many patented technologies simply because it is so large and complex. But if these many technologies are very distinct from one another, then no thicket problems will arise. Rather, patent thicket problems arise when there are closely related technologies whose patents have overlapping or redundant protective boundaries, making it difficult to say whether one firm’s technology infringes on another’s patent.


    I don’t think many scholars have argued that a large number of patents is always sufficient for a patent thicket. They might argue that the issues that enable a patent thicket to arise usually lead to a large surplus of patents, however, in which case Lemley’s comment still has merit. A patent thicket is simply a collection of patents plagued by overlapping or obscure protective boundaries. When such patents are easy to obtain (as in the software industry, for example), firms will frequently have an incentive to acquire them, if for no other reason than to defend against bogus infringement claims. This may lead to a surplus of patents. So, if the relationship is causal, it’s probably in the other direction.

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