This paper examines whether an appropriate legal system, which is a combination of a legal regime and a damage apportionment rule, effectively enhances auditor independence. Economic and psychological hypotheses derived from a one-period game model in which the auditor may commit either a technical audit failure (resulting from the auditor’s inability to detect true output given a lack of audit effort) or an independence audit failure (resulting from the auditor’s intentional misreporting on false output) are tested. Three major findings are documented. First, auditor independence affects firm investment, which in turn affects audit effort. Under this strategic dependence, no single legal system can provoke audit effort, improve auditor independence, and encourage firm investment simultaneously. To enhance auditor independence and motivate investment, a legal system consisting of both a strict regime and a proportionate rule is preferred. Second, the strict regime induces more auditor independence than the negligence regime, while the proportionate rule induces higher audit effort than the joint-and-several rule. Finally, auditors’ moral reasoning and penalty for misreporting are both positively associated with their independence. In addition, the effect of moral reasoning on auditor independence diminishes as the level of penalty increases. These two results hold only when the legal systems that auditors face are considered.