The California Land Act of 1851 (9 Stat. 631), enacted following the Treaty of Guadalupe Hidalgo and the admission of California as a state in 1850, established a three-member Public Land Commission to determine the validity of prior Spanish and Mexican land grants.[1] It required landowners who claimed title under the Mexican government to file their claim with a commission within two years. Contrary to the Treaty of Guadalupe Hidalgo, which guaranteed full protection of all property rights for Mexican citizens, it placed the burden on landholders to prove their title.
While the commission eventually confirmed 604 of the 813 claims, almost all of the claims went to court and resulted in protracted litigation. The expense of the long court battles required many land holders to sell portions of the property or even trade it in payment for legal services. A few cases were litigated into the 1940s.