In the case of Parker et al. v. County of Los Angeles et al., 1949, the Supreme Court ruled in favor of Los Angeles County and against a group of African American homeowners who had purchased homes in an area zoned for "A1" use, which included single-family dwellings but excluded apartment houses, hotels or sanitariums. The plaintiffs argued that this zoning ordinance violated their Fourteenth Amendment rights because it was racially discriminatory; they claimed that its true purpose was to prevent them from living in a predominantly white neighborhood. The court rejected these claims on two grounds: first, there was no evidence presented to suggest racial discrimination by the county's Board of Supervisors when enacting or enforcing this ordinance; secondly, even if such evidence existed, it would not be sufficient to invalidate a law unless it could be proven that the law itself is unjustifiable and serves no legitimate public interest. Therefore, since zoning laws are generally accepted as serving valid public interests (such as maintaining property values), and since there were other areas within Los Angeles where multi-dwelling buildings were permitted - thus providing alternative housing options for those affected by this particular ordinance - the court found no violation of equal protection under the Constitution.

In the dissenting opinion for Parker et al. v. County of Los Angeles et al., Justice Jackson disagreed with the majority's decision to uphold a California law that allowed counties to charge non-residents higher hospital fees than residents. He argued that this policy violated the Privileges and Immunities Clause of Article IV, Section 2, which guarantees citizens in each state all privileges and immunities granted to citizens in other states. According to Justice Jackson, medical care is a privilege; therefore, it should be equally accessible regardless of residency status under federal law. Furthermore, he contended that such discriminatory practices could lead to retaliatory measures from other states against Californian residents seeking medical services outside their home state - an outcome contrary to national unity and harmony among different jurisdictions within America.