Pierson v. Post, 3 Cai. R. 175, 2 Am. Dec. 264 (N.Y. Sup. Ct. 1805)
Pierson v. Post (1805) is the quintessential first-year property law case, introducing students to fundamental concepts of property acquisition and the rule of capture.
Does a person acquire property rights in a wild animal by pursuing it with the intent to capture it, or is actual capture required to establish ownership?
Property rights in wild animals (ferae naturae) are acquired only through actual capture or mortal wounding followed by continued pursuit. Mere pursuit, even with intent to capture, does not establish property rights. The rule of capture requires either physical possession or circumstances that make capture inevitable.
The court held that Post did not acquire property rights in the fox through mere pursuit. Pierson, who actually killed and captured the fox, acquired ownership. Post's pursuit alone was insufficient to establish a property claim.
This case established the fundamental rule of capture in property law and demonstrates how legal systems create clear rules for acquiring property rights in unowned resources. The principle extends beyond hunting to oil, gas, water, and other natural resources. It illustrates the tension between rewarding effort and providing legal certainty.