In the wake of Japan’s attack on Pearl Harbor, the U.S. government forced more than 100,000 Japanese Americans into prison camps during World War II. One of those Japanese Americans, Fred Korematsu, would later contend the act had violated his constitutional rights.

In 1944, the U.S. Supreme Court ruled against Korematsu and backed the government’s action in Korematsu v. United States, a decision that historians and legal experts alike have since argued was incorrect. On Tuesday, the Supreme Court had a chance to overturn the 1944 ruling if it rejected Donald Trump’s travel ban. Instead, the court condemned Korematsu while still upholding the travel ban in a 5-4 vote—meaning that the 1944 decision still technically stands, according to a legal expert.

“A case can only overrule a previous case if the two cases raise the same issue, and if getting to the result in the later case requires going against the decision in the earlier case,” explains Richard Primus, a constitutional law professor at the University of Michigan. “A court only has authority to do what is part of deciding this case, and there is nothing about [the travel ban] decision that contradicts anything in Korematsu.”

Put another way: In order to rule against school segregation in Brown v. Board of Education, the court had to overrule Plessy v. Ferguson because it legalized racial segregation. In contrast, it is not necessary for the court to overturn Korematsu to uphold the travel ban in Trump v. Hawaii.

When the Supreme Court upheld Donald Trump’s travel ban targeting seven nations, five of which are majority-Muslim, Justice Sonia Sotomayor warned in her dissent that upholding the ban would echo the Court’s 1944 decision supporting Japanese internment in Korematsu v. United States. Despite the fact that Chief Justice John Roberts called the 1944 ruling on internment “wrong” in the court’s decision, Korematsu still stands.

In the Korematsu decision, the court ruled that the U.S. had not violated the constitutional rights of Japanese-American citizen Fred Korematsu by incarcerating him during World War II. While most legal experts disagree with that the decision today, there has been no ruling since then in which the court has had the opportunity to overturn Korematsu by overturning another policy on similar grounds. The only way Trump v. Hawaii could’ve overturned Korematsu was if the court had rejected the travel ban. And indeed, legal experts like Primus thought that if the court ruled this way, it would take the opportunity to overrule Korematsu.

In her Trump v. Hawaii dissent, Sotomayor drew parallels between Japanese internment and the travel ban, arguing that in both cases, “the Government invoked an ill-defined national security threat to justify an exclusionary policy of sweeping proportion.” These exclusionary policies, she wrote, were “rooted in dangerous stereotypes.” Just as the government argued without evidence that Japanese Americans were disloyal and couldn’t be trusted, she argued that the travel ban is based on stereotypes of Muslims as a dangerous ethnic-religious group rather than legitimate national security concerns.

Chief Justice John Roberts disagreed with Sotomayor’s point in his majority opinion, writing that the two policies had nothing to do with each other. To underline his argument, he wrote that “Korematsu was gravely wrong the day it was decided, has been overruled in the court of history, and—to be clear—‘has no place in law under the Constitution.’”

But although Roberts writes that he disagrees with the constitutionality of Korematsu and that history has disagreed with it, he doesn’t write that the Trump decision officially overrules Korematsu—because it doesn’t.

Primus doesn’t think that Korematsu will necessarily be used to hold up similar decisions in the future. However, he does qualify this by noting that Trump cited Japanese internment during his campaign as precedent for his proposed Muslim ban.

“I think that we have seen over the last couple of years that a lot of things that we thought were safe and settled are not safe and settled,” he says. “And there’s no guarantee that the idea that Korematsu was wrong is one of them.”