In the thick of his argument defending President Donald Trump’s travel ban earlier this week, a top lawyer for the Department of Justice was thrown a curveball from a dark period in American history.

Richard Paez, a judge on the U.S. Court of Appeals for the 9th Circuit, asked Jeffrey Wall, the acting solicitor general, if the government’s case for the executive order banning travelers from six Muslim-majority countries resembled the legal justifications for the displacement and incarceration of Japanese-Americans during World War II.

Without addressing the question head-on, Wall rejected the comparison.

“This case is not Korematsu, and if it were, I wouldn’t be standing here and the United States would not be defending it,” Wall proclaimed, alluding to the landmark Supreme Court ruling that upheld the conviction of Fred Korematsu, a California man who defied the military exclusion order that forcibly removed and effectively imprisoned 120,000 Japanese-Americans during the war. About two-thirds of those incarcerated were U.S. citizens, and many were children.

Justice Frank Murphy, one of the three justices who dissented in the 1944 Korematsu decision, likened his colleagues’ ruling to the “legalization of racism.”

The exchange was a marquee moment during this week’s court hearing — one of two that could decide the fate of Trump’s so-called “Muslim ban.” Trump’s executive order hasn’t been enforced since a pair of federal judges put it on hold after concluding that it was driven by unconstitutional animus against Muslims.

MANDEL NGAN via Getty Images A portrait of Fred Korematsu hangs in the National Portrait Gallery on Feb. 2, 2012 in Washington, D.C.

The exchange was also a highlight for the Fred T. Korematsu Center for Law and Equality, housed at the law school at Seattle University, which filed one of dozens of friend-of-the-court briefs from around the country opposing Trump’s travel restrictions. In his question to Wall, Judge Paez specifically singled out the arguments laid out in the center’s brief.

“The Supreme Court’s decision in Korematsu gave virtually a blank check to the Executive Branch to take action against disfavored minorities in the name of national security,” read the center’s brief, which also listed as signatories Korematsu’s daughter and the children of other Japanese-Americans who challenged the U.S. government’s discriminatory wartime policies in court.

For Robert Chang, the executive director of the Korematsu Center, the mention of his team’s work in such a prominent session gave them a thrill they weren’t expecting — and inspired hope that the courts will reclaim their place in the system of checks and balances.

“To the extent that this pushes and really reasserts the judiciary and its role as acting as a check of the excesses of Congress and the executive, that’s our democratic system,” Chang said in an interview.

Korematsu v. United States — a discredited court decision that affirmed the legality of Japanese-Americans’ wartime incarceration — is not directly implicated in the travel ban challenge filed by the state of Hawaii that is pending before the 9th Circuit. To date, the ruling is an anti-canon in American law: Even though it has never been overturned, there’s wide consensus that it was wrongly decided and should be given no weight as legal precedent.

In 1988, the U.S. government formally apologized for Japanese-Americans’ wartime experiences ― saying they were “motivated largely by racial prejudice, wartime hysteria, and a failure of political leadership” ― and issued reparations to survivors. Years later, the Justice Department confessed error over its role in these cases.

Still, Korematsu reared its head at two recent court hearings examining the legality of Trump’s executive order, both times at the behest of judges.

Last week, James Wynn, a judge on the federal appeals court based in Richmond, Virginia, wondered what would happen if his court accepted one of Trump’s rationales for the travel ban — a blanket assertion by the president that his order is intended to protect the country from foreign threats.

“If we followed that line of reasoning, would we think differently of Korematsu now? Can we follow that reasoning?” Wynn asked. “If we don’t lock them all up and something bad happens, then it’s on the president. If we do, then you violate the law.”

The balance between protecting national security and constitutional rights is as old as the republic, and the two courts now considering the travel ban could well choose to put those two interests on the scale.

But in the travel ban litigation, the Trump administration has pushed courts to not even walk that line, urging them instead to completely defer to the government because judges shouldn’t second-guess the president’s judgment in the immigration realm — where Congress has vested the executive with broad powers to exclude non-citizens.

If we followed that line of reasoning, would we think differently of Korematsu now? U.S. Circuit Judge James Wynn

In its brief, the Korematsu Center contends that American history teaches the opposite: That government action that paints an entire group with a broad brush should be subject to tough judicial scrutiny, and that anything less would be an abdication of courts’ constitutional role.

The Korematsu decision “remains a black mark on our Nation’s history and serves as a stark reminder of the dire consequences that result when abuses by the political branches go unchecked by the Judiciary,” observes the brief.

It remains to be seen whether the upcoming rulings will name-check Korematsu. At least one legal scholar has made a case that courts should resist that temptation — in part because there are critical differences, constitutionally speaking, between executive actions that discriminate against U.S. minorities and those that target people outside the U.S.

The courts, and eventually the Supreme Court, will settle that and other issues implicated in the travel ban cases.

Back at the Korematsu Center — where a picture of Korematsu and Rosa Parks standing together is visible — Chang said the travel ban case reminds him of the center’s broader mission and “serves as a reminder about the courage of ordinary people.”

“What I would love for people to learn from Fred and Rosa Parks’ example,” Chang said, “is that change comes about when people say ‘no’ to abuses of power. Change comes about when people say ‘no’ to discrimination.”