The Information Value of Patent Claims
- Author(s): Tun-Jen Chiang
- Date Posted: August 2012
- Law & Economics #: 12-51
- Availability: Full text (most recent) on SSRN
It is axiomatic that patent “claims” define the scope of the monopoly. The standard justification for this doctrine is the notice theory, where claim text is supposed to accurately describe the invention so that competitors know what is protected. This theory, however, has a problem: Because claims are written by self-serving patentees, they predictably overreach and do not describe the real invention. Due to this fact, a large literature argues that patent claims are valueless and should be abolished or ignored.
This Article defends patent claims by articulating a new theory. The point of claims is not to provide a perfect description of the invention, as the notice theory posits. Rather, the point of claims is to provide imperfect information about the invention. The key is that even a slanted claim is better than no claim at all, because courts have no ready way to calculate the correct scope of a patent from scratch. An analogy to contracts of adhesion illustrates the intuition. Like patent claims, contracts of adhesion are self-servingly drafted. Yet such documents are still valuable to courts, because the alternative is for a court to reconstruct the bargain ex post using oral testimony, which is not feasible due to high information costs.
The fact that claims provide valuable-but-biased information leads to a conundrum. In order to create an incentive for patentees to draft claims (and disclose information), courts should enforce the resulting text as written. But, in any individual case, a court can create better outcomes by adjusting the claim downward using other sources of interpretative evidence. The result is that courts must balance these competing considerations by giving significant, but not conclusive, interpretative weight to claim text—which is exactly what happens in real life. In this way, the information cost theory provides both a positive explanation for existing practice and a limited normative defense of textualism in patent law.