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. 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.