California Penal Code section 597t

Section 597t of the Penal Code of California is a California State criminal law which requires that animals confined in enclosed areas be provided with an adequate exercise area. Even though this section of the Penal Code does not define "adequate exercise area", it would seem to prohibit the confinement of calves in veal crates, as well as the confinement of hens in battery cages and the confinement of sows in gestation crates.

Source: Wikipedia — California Penal Code section 597t (CC BY-SA 4.0)