How does trade secrecy affect patenting?

As I mention in my forthcoming book chapter on empirical methods in trade secret research, there's really a dearth of good empirical scholarship about the role of trade secrets in the economy. One scholar who has written several articles in this area is my Ivan Png from the National University of Singapore. Professor Png exploits the variation in strength of trade secret protection to find causal effects on, say, innovation or worker mobility.

His latest article, called Secrecy and Patents: Theory and Evidence from the Uniform Trade Secrets Act (SSRN draft here, Final paywall version here), examines how rates of patenting change when levels of protection for trade secrets change. Here is the abstract, which shares some of findings:

How should firms use patents and secrecy as appropriability mechanisms? Consider technologies that differ in the likelihood of being invented around or reverse engineered. Here, I develop the profit-maximizing strategy: (i) on the internal margin, the marginal patent balances appropriability relative to cost of patents vis-a-vis secrecy, and (ii) on the external margin, commercialize products that yield non-negative profit. To test the theory, I exploit staggered enactment of the Uniform Trade Secrets Act (UTSA), using other uniform laws as instruments. The Act was associated with 38.6% fewer patents after one year, and smaller effects in later years. The Act was associated with larger effect on companies that earned higher margins, spent more on R&D, and faced weaker enforcement of covenants not to compete. The empirical findings are consistent with businesses actively choosing between patent and secrecy as appropriability mechanisms, and appropriability affecting the number of products commercialized.

Frankly, I think that the abstract undersells the findings a bit, as it seems targeted to the journal, "Strategy Science." The paper takes a much broader view of his model: "If trade secrets law is stronger in the sense of reducing the likelihood of reverse engineering, then businesses should adjust by (i) patenting fewer technologies and keeping more of them secret, and (ii) commercializing more products."

Like Png's other work in this area, the core of the analysis begins with an index of trade secret strength in each state, based on passage of the UTSA and variations of each state's implementation of UTSA (e.g. with respect to inevitable disclosure). In this paper, Png then obtained data about the location of company R&D facilities and patents coming out of those facilities. He also used other uniform laws passed at around the same time as an instrument, to make sure that the UTSA is not endogenous with patenting.

This is a really interesting and important paper, even if it validates what most folks probably assumed (dating back to the days of Kewanee v. Bicron): if you strengthen secrecy, there will be fewer patents. That said, there is a lot going on in this paper, and a lot of assumptions in the modeling. First and foremost, the levels of protection of trade secrets don't have many degrees of freedom. I much prefer the categories created by Lippoldt and Schultz. That said, even a binary variable might be sufficient. Second, the model and estimation are based on the assumption that the marginal patent is the one most likely to be designed around, and uses the number of technology classes to estimate patent scope (and validate the assumption). I know many folks who would disagree with using patent classes as a measure of scope.

Even with these critiques, this paper is worth a read and some attention. I'd love to see more like it.