LA County
The Leash Law: It is not permissible to let your dog run at large day or night, with or without a license (County Code Title 10, Section 10.32.010).
San Bernardino County Leash Law
San Bernardino County law (Code: 32.0108 Control of Animals) requires all animals to be restrained whenever they are on public property or unenclosed private property.
A person having custody of any dog shall not permit, either willfully or through failure to exercise due care or control, any such dog to defecate or urinate upon a public street or sidewalk; the floor of any common hall in any apartment house, hotel, or other multiple dwelling; upon any entrance way, stairway, or wall immediately abutting on a public sidewalk; or upon the floor of any theater, shop, store, office building, or other building used by the public.