James E. Bessen

Sequential Innovation, Patents, and Imitation

We argue that when innovation is “sequential” (so that each successive invention builds in an essential way on its predecessors) and “complementary” (so that each potential innovator takes a different research line), patent protection is not as useful for encouraging innovation as in a static setting. Indeed, society and even inventors themselves may be better off without such protection. Furthermore, an inventors prospective profit may actually be enhanced by competition and imitation. Our sequential model of innovation appears to explain evidence from a natural experiment in the software industry.

The Value of U.S. Patents by Owner and Patent Characteristics

This paper uses renewal data to estimate the value of U.S. patents, controlling for patent and owner characteristics. Estimates of U.S. patent value are substantially larger than estimates for European patents, however, the ratio of U.S. patent value to R&D for firms is only about 3%. Patents issued to small patentees are much less valuable than those issued to large corporations, perhaps reflecting imperfect markets for technology. Litigated patents are more valuable, as are highly cited patents. However, patent citations explain little variance in value, suggesting limits to their use as a measure of patent quality.

The Patent Litigation Explosion

This paper provides the first look at patent litigation hazards for public firms during the 80s and 90s. Consistent with our model, litigation is more likely when prospective defendants spend more on R&D, when prospective plaintiffs acquire more patents and when firms are larger and technologically close. Public firms face dramatically increased hazards of litigation as plaintiffs and even more rapidly increasing hazards as defendants, especially for small public firms. The increase cannot be explained by patenting rates, R&D, firm value or industry composition. Legal changes are the most likely explanation.

The Private and Social Costs of Patent Trolls

In the past, non-practicing entities (NPEs) — firms that license patents without producing goods — have facilitated technology markets and increased rents for small inventors. Is this also true for today’s NPEs? Or are they “patent trolls” who opportunistically litigate over software patents with unpredictable boundaries? Using stock market event studies around patent lawsuit filings, we find that NPE lawsuits are associated with half a trillion dollars of lost wealth to defendants from 1990 through 2010, mostly from technology companies. Moreover, very little of this loss represents a transfer to small inventors. Instead, it implies reduced innovation incentives.

Patent Thickets: Strategic Patenting of Complex Technologies

Patent race models assume that an innovator wins the only patent covering a product. But when technologies are complex, this property right is defective: ownership of a product’s technology is shared, not exclusive. In that case I show that if patent standards are low, firms build “thickets” of patents, especially incumbent firms in mature industries. When they assert these patents, innovators are forced to share rents under cross-licenses, making R&D incentives sub-optimal. On the other hand, when lead time advantages are significant and patent standards are high, firms pursue strategies of “mutual non-aggression.” Then R&D incentives are stronger, even optimal.

Patents and the Diffusion of Technical Information

Does the disclosure requirement of the patent system encourage the diffusion of inventions? This paper builds a simple model where firms choose between patents and trade secrecy to protect inventions. Diffusion is not necessarily more likely with a patent system nor is the market for technology necessarily greater.

The Private Costs of Patent Litigation

This paper estimates the total cost of patent litigation to alleged infringers. We use a large sample of stock market event studies around the date of lawsuit filings for US public firms from 1984-99. We find that the total costs of litigation are much greater than legal fees and costs are large even for lawsuits that settle. Lawsuits cost alleged infringers about

Estimates of Patent Rents from Firm Market Value

28.7 million (

Do Patents Perform Like Property

92) in the mean and

Technology and Learning by Factory Workers: The Stretch-Out at Lowell, 1842

2.9 million in the median. Moreover, infringement risk rose sharply during the late 1990s to over 14% of R&D spending. Small firms have lower risk relative to R&D.