John Allison, Mark Lemley & Joshua Walker continue to mine information from Stanford's IP Litigation Clearinghouse and have come up with a new study titled "Extreme Value or Trolls on Top? The Characteristics of the Most-Litigated Patents."
The authors sifted through mounds of data to identify the patents litigated most frequently between 2000 and 2007, and compare those patents to a control set of patents that have been litigated only once in that period. As a benchmark, the "most litigated" patents were those that were litigated eight or more times during the time period, and the study identified 106 such patents (astoundingly, one of the patents on the list was litigated 97 times). Altogether, these 106 patents accounted for 2,987 infringement suits represent about 14% of the patent suits filed from 2000 through 2007.
After breaking the patents down into technology areas, industry areas, "NPE Class" owner, and patent characteristics, a number of observations were made:
With regard to technological areas:
• The most-litigated patents made extraordinary use of patent continuations. Litigated patents in the control set had an average of two priority applications – the original application and one continuation or divisional. And fully half of the patents in the control set filed no continuation applications at all. By contrast, the most-litigated patents had an average of 4.3 applications each, and the median patent in this set had three applications.
• The most-litigated patents are cited more than twice as often as the control set patents. After adjusting the number of forward citations received by patents to account for their different ages, the differences between the two data sets are significant to an exceptional degree.
• The most litigated patents more than 50% more claims than the control set, 39.3 on average compared with 24.5 for once-litigated patents.
• The most-litigated patents cite nearly three times as many U.S. and foreign patents as other litigated patents, and nearly ten times as many non-patent prior art references as other litigated patents.
When considering the nature of the patent owner:
• The most-litigated patents are overwhelmingly likely to be software patents. Nearly three-fourths of the most-litigated patents are software patents, compared with just over a quarter of the once-litigated patents. Similarly, software-implemented business method patents are overrepresented in the most-litigated patents group (15% vs. 4%).
• Imaging patents are much more heavily represented in the most-litigated category (11% vs. 2%) as well.
• By contrast, mechanical and electronics patents make up the bulk of the once litigated patent cases, but they are only of minor significance in the most-litigated patent set. Mechanical inventions make up only 8% of the most-litigated patents, but 53% of the once-litigated patents; electronics inventions make up only 1% of the most-litigated patents but fully 25% of the once-litigated patents.
To read more about this, other findings, and a full listing of the most-litigated patents, see "Extreme Value or Trolls on Top? The Characteristics of the Most-Litigated Patents" (link)
• Traditional product companies – those who are participants in the market in which they are enforcing the patent – represent 83.3% of the once-litigated patents but only 45.6% of the most-litigated patents.
• More than 80% of the most litigated patent suits are filed by NPEs. Overwhelmingly these are filed by inventor-owned or inventor-developed companies; those companies account for 74.4% of the most-litigated patent lawsuits. The share of suits filed by licensing shops actually falls to 6.7% of all suits. Non-practicing entities are a small share of once-litigated patents, but they represent an overwhelming share of the suits filed on the most-litigated patents.
• NPE's fall almost entirely into only two classes: licensing companies who are in the business of buying up and enforcing patents (“trolls” by virtually anyone’s definition) and companies started by the inventor but which do not make products. Licensing companies account for 11.7% of the most-litigated patent suits, and inventor companies account for 41.7% of those suits.