Lum v. Robertson was a United States Supreme Court case that dealt with the issue of racial discrimination in the public school system. The case was brought by a Chinese-American student, Ah Lum, who was denied admission to a public school in San Francisco on the basis of his race. The school argued that it was within its rights to deny admission to Lum because of a California law that prohibited non-white students from attending public schools. The Supreme Court ruled in favor of Lum, finding that the California law was unconstitutional. The Court held that the law violated the Equal Protection Clause of the Fourteenth Amendment, which prohibits states from denying any person the equal protection of the laws. The Court also held that the law violated the Privileges and Immunities Clause of the Fourteenth Amendment, which prohibits states from denying any person the privileges and immunities of citizens of the United States. The Court's decision in Lum v. Robertson was a landmark ruling that established the principle that racial discrimination in public schools is unconstitutional. The ruling was an important step in the fight for racial equality in the United States and helped pave the way for the desegregation of public schools in the years to come.

In the case of Lum v. Robertson, Chief Justice Chase delivered a dissenting opinion in which he argued that the majority's decision was inconsistent with prior Supreme Court decisions and would lead to an unjust result for the plaintiff. He noted that under existing law, African Americans were not allowed to testify against whites in court proceedings and thus could not be held liable for debts owed by them. Furthermore, he argued that allowing such testimony would open up a Pandora's box of potential litigation between white creditors and black debtors who had no legal recourse due to their inability to testify against each other. Ultimately, Chief Justice Chase concluded that it was unfair for one party (the creditor) to benefit from this inequality while another (the debtor) suffered as a result of it; therefore, he believed the majority should have reversed the lower court’s ruling instead of affirming it.