The California Land Act of 1851 was a law established to address land claims in California after it became a U.S. state in 1850. The act aimed to clarify and confirm land titles that were granted under the previous Mexican government. It required landowners to prove their ownership through legal documentation, which often led to disputes and challenges. To enforce the act, a Board of Land Commissioners was created to review claims. This process was significant in shaping land ownership in California, as many settlers faced difficulties in proving their rights, leading to a complex legal landscape regarding land ownership in the state.