The Evolution of Common Law
构建了一个上诉法院造法模型，法官受政策偏好影响，可以花费成本区分先例。研究发现，司法观点的多样性既有成本也有收益：政策导向的法官会扭曲法律效率，但多样性也促进法律演进并提高法律精确性。核心结论是“卡多佐定理”：即使法官受个人议程驱动，法律演进平均而言是有益的，因为它能消除司法偏见并使法律更精确。
We present a model of lawmaking by appellate courts in which judges influenced by policy preferences can distinguish precedents at some cost. We find a cost and a benefit of diversity of judicial views. Policy-motivated judges distort the law away from efficiency, but diversity of judicial views also fosters legal evolution and increases the law’s precision. We call our central finding the Cardozo theorem: even when judges are motivated by personal agendas, legal evolution is, on average, beneficial because it washes out judicial biases and renders the law more precise. Our paper provides a theoretical foundation for the evolutionary adaptability of common law.