Policy, scholarly, and popular discussions of the socially desirable level of protection provided by intellectual property rights typically take for granted that changes in the level of intellectual property protection matter a great deal. It is commonly assumed to make a substantial difference in regulating access to intellectual goods whether patent claims are broadly or narrowly interpreted, the copyright term is longer or shorter, or the fair use exemption is applied more or less generously. This assumption follows what appears to be an uncontroversial proposition commonly set forth in intellectual property jurisprudence and scholarship: patents, copyrights, and other entitlements determine which technologies and creative works fall into the private domain (to which access is constrained) and which remain in the public domain (to which access is unfettered). In this Article, I show that this proposition should be controversial. It is not clear that changes—even substantial changes—in intellectual property protection typically make any meaningful difference in regulating access to the underlying pool of intellectual goods, which in turn means that these changes do not clearly make any meaningful difference in regulating the anticipated profits that drive innovation incentives. Contrary to natural intuitions, the size of the public domain may be substantially invariant to changes in intellectual property coverage. This qualified indifference thesis is founded in a well-established empirical observation: firms generally can—and do—exploit devices other than intellectual property to limit access to, and thereby appropriate returns from, innovation investments. Hence, intellectual goods that are unprotected by intellectual property may still be protected directly or indirectly by other legal or extralegal mechanisms, which broadly include technology, contract, organizational form, and various complementary assets.

If these alternative instruments can substantially replace the appropriation capacities provided by intellectual property rights, then legal changes that constrain those rights and thereby ostensibly expand the public domain have no substantial net effect; conversely, if these alternative instruments can match or exceed the appropriation capacities provided by intellectual property rights, then legal changes that expand these rights and thereby ostensibly narrow the public domain have no substantial net effect. This proposition is self-evidently true in the extreme case where perfect technological locks can be implemented at zero cost: contractions or expansions in intellectual property coverage have no marginal effect on the access costs incurred by third parties and, as a consequence, on the innovation gains anticipated by resource holders. In a broader class of intermediate settings, this proposition retains descriptive force to the extent that firms can exploit alternative instruments substantially to reproduce, or even surpass, the appropriation capacities provided by intellectual property.