Was California in 1848 under Mexico laws?

Yes, in 1848 California was under Mexican laws. During the Mexican-American War (1846–1848), the United States invaded and occupied California, which was then part of Mexico. The war ended with the signing of the Treaty of Guadalupe Hidalgo in 1848, which resulted in the United States acquiring California and other territories from Mexico. However, California remained under Mexican laws until the passage of the California Constitution in 1849, which established California as a state of the United States.