Hans v. Louisiana was a Supreme Court case decided in 1890. The case involved a challenge to a Louisiana law that prohibited non-citizens from suing in state court. The plaintiff, a German citizen, argued that the law violated the Privileges and Immunities Clause of the Fourteenth Amendment. The Supreme Court ruled in favor of the plaintiff, finding that the law violated the Privileges and Immunities Clause. The Court held that the clause protected the right of non-citizens to sue in state court, and that the law was an unconstitutional infringement on that right. The Court also noted that the law was discriminatory, as it only applied to non-citizens and not citizens. The decision in Hans v. Louisiana was significant in that it established the principle that non-citizens have the same rights as citizens when it comes to access to the courts. The decision also established the principle that laws which discriminate against non-citizens are unconstitutional.

In the case of Hans v. Louisiana, Justice Harlan delivered a dissenting opinion in which he argued that the Fourteenth Amendment's Privileges and Immunities Clause should protect citizens from being deprived of their property without due process. He asserted that this clause was intended to provide protection against state action, not just federal action as had been previously held by the Court. Furthermore, he argued that it would be unjust for states to be able to take away an individual's rights without providing them with any form of legal recourse or compensation for their losses. In conclusion, Justice Harlan believed that if the Court were to uphold its previous ruling on this matter then it would effectively render meaningless much of what is contained within the Fourteenth Amendment and thus undermine its purpose entirely.