(CNN) On June 7, 1892, a dapper shoemaker purchased a first-class ticket on a Louisiana train for a short journey he knew he wouldn't finish .

The 30-year-old man of mixed-race heritage sat in the whites-only section of the train. When a conductor ordered him to move to a dingy rail car reserved for blacks, he refused, was arrested and convicted at a trial.

The man appealed his case to the Supreme Court. Four years later, the court rejected his claim that sitting in a segregated train car stamped him with "a badge of servitude."

The New York Times published only two paragraphs on the 7-1 decision. But Homer Adolph Plessy, the man on the train, did not fade from history. Plessy v. Ferguson eventually became known as one of the Supreme Court's most nakedly racist decisions. The 1896 ruling played a pivotal role in giving legal cover to Jim Crow segregation that would last for more than half a century.

It's hard today not to marvel at the casual cruelty of the Plessy decision. How could the court accept the transparent lie that blacks lived in separate but equal worlds with whites? And how could they give Constitutional sanction to a blatant display of racism?

You don't have to study history to answer those questions. Watch what happens this week when the US Supreme Court issues its decision on whether the Trump administration can add a question about citizenship to the 2020 census , some legal scholars and historians say.

They say the conservative majority on the court is on the verge of embracing some of the same legal rationalizations that produced Jim Crow segregation in the census case.

"If they accept the census question, they are following the same pattern that the late-19th-century and 20th-century court made that was clearly intended to cement white rule," says Lawrence Goldstone, author of "Inherently Unequal: The Betrayal of Equal Rights by the Supreme Court, 1865-1903."

A court that sees and hears no evil

The case revolves around a simple request. The Trump administration says it wants the Census Bureau to ask residents whether they are US citizens. The Department of Justice says it would help ensure the voting rights of racial minorities.

Some court watchers expect they will and that they will do this by borrowing some of the same tactics their counterparts used in the late 19th century to legitimize Jim Crow segregation.

The Plessy v. Ferguson decision gave legal cover to Jim Crow segregation laws.

The formula for this version of White Supremacy 2.0 is the same as it was then: Ignore the racist intent behind laws to justify a preordained decision, says Goldstone, author of "Inherently Unequal."

"If the Court chooses to pretend that what was said was not said, and that blatant motive is not relevant, we are back to the late 19th century indeed," Goldstone says after citing evidence alleging that the Trump administration isn't being honest about why it wants to add a citizenship question to the census.

"In criminal cases, motive and intent is everything. Why not here?" Goldstone says. "Lady Justice may be blind, but it shouldn't be dumb."

Supporters of the citizenship question say, though, that its purpose is actually protecting racial minorities. The Commerce Department has said it wants to add the citizenship question because it would bolster the government's efforts to enforce the Voting Rights Act.

Besides, other countries include a citizenship question on their census. Why not America, says Hans von Spakovsky with the Heritage Foundation, a conservative think tank.

"We have also been in the midst of a contentious debate for more than a decade about immigration," Spakovsky wrote. "To have an informed debate, shouldn't we have accurate information about the citizen/noncitizen population of the country?"

White supremacy 2.0?

So is it really fair to compare a modern-day question about administering the census to a white-supremacist era where thousands of newly freed slaves throughout the South were lynched for offenses ranging from holding elected office to attempting to vote?

And how can one compare a court that legalized same-sex marriage nationally to its counterpart in the 19th century, which played a decisive role in destroying Reconstruction, the nation's first attempt at a multiracial democracy?

That court systematically dismantled laws such as the 1875 Civil Rights Act, which banned discrimination in public places such as trains and hotels. And historians say it transformed the 14th Amendment, which was designed to protect the basic rights of newly freed slaves, into a weapon to boost the power of corporations

Plessy, the man who took the historic train ride, still had hope in the Supreme Court of his era. His trip wasn't random. He was an activist who stepped in the whites- only railroad car expecting to be arrested.

Some scholars also believe the 1896 Supreme Court ruling emboldened white supremacists in the early 1900s.

He wanted to challenge a Louisiana state law passed two years earlier that required "equal but separate accommodations for white and colored races." In his case against John Howard Ferguson, the Louisiana judge who convicted him, he said it violated his constitutional guarantee of equal rights.

But white supremacy is not confined to racist judges from another era. Some say it is also about preserving white dominance over other racial groups in all sorts of subtle ways.

Adding a citizenship question to the census would be a naked grab for white power , some say.

They say the Constitution holds that Congress must count how many people -- not citizens -- live in the country. That number is used to determine everything from the number of representatives in the House to how much federal funding a state gets.

Critics of the census-citizenship question argue it would suppress the political power of Latinos.

Ibram X. Kendi, author of "How to be an Antiracist," says the Trump administration citizenship request is a modern manifestation of racism because it is driven by the same impulse that drove white supremacists in the South during Jim Crow.

In the Jim Crow South, there were many regions where newly freed slaves outnumbered whites. But whites used vigilante mob violence and the passage of "black codes" to maintain their power.

"They're trying to figure out a way to maintain white supremacy in the race of changing demographics," says Kendi when asked about the purpose behind the census citizenship question. "You certainly have white supremacists who burn crosses. Then you have the white supremacists that push through voter ID laws to ensure that certain populations are suppressed specifically so that white voters can have a disproportionate amount of power."

When the court looks the other way

Big questions about political power often end up before the Supreme Court, especially when the topic involves race.

Yet the Supreme Court has still found ways in the past to ignore or deflect ample evidence of racism and bigotry in some of its most important decisions.

Conservatives on the contemporary Supreme Court have already shown how that's done when they upheld President Trump's travel ban on immigrants from some Muslim-majority countries last year, critics say. They defer to authority instead of confronting the racist intent behind some laws, some say.

In " Trump v. Hawaii ," Chief Justice John Roberts acknowledged Trump's previous statements calling for a "total and complete shutdown of Muslims entering the United States" as well as other incendiary statements against Muslims.

Roberts said, though, that the issue before the court was not whether or not to denounce Trump's statements. The court must also consider " the authority of the presidency itself," he wrote

In 1944 the Supreme Court upheld the internment of Japanese Americans during World War II.

Noah Feldman, a legal historian and Harvard Law School professor, said "Trump v. Hawaii" was the court's worst decision since the infamous Korematsu case of 1944, in which the court upheld the internment of Japanese Americans during World War II on grounds that it was a "military necessity."

"Like the Korematsu decision, Trump v. Hawaii elevates legal formalities as a way to avoid addressing what everyone understood is really at issue here — namely, prejudice," Feldman wrote in a column

Another legal historian sees the same deft avoidance of confronting prejudice while listening to the oral arguments in the census case.

Peter Irons, author of "A People's History of the Supreme Court," says he was struck by how the court's conservative justices evaded the case's central question: Did the Trump administration add the citizenship question to the census to boost white Republican power at the expense of Latinos?

Instead the conservative justices focused on tangential questions revolving around the Trump administration's authority to add the question, he says.

"What the court does -- and the court does this often -- is evade reality," Irons says. "It allows them to focus on technical questions. "

How the Plessy playbook plays out today

The court's 19th-century counterparts did the same in the Plessy v. Ferguson case, Irons says.

The justices who ruled against Plessy didn't bother to confront the white-supremacist thinking that formed the backdrop of the case. They decided instead that they had to honor the authority of the state of Louisiana to make its own laws, Irons says.

"The court deferred to their justification, which was clearly racist," Irons says. "The lawyer for the state of Louisiana said white people don't want to ride on the same coaches because black people smell bad. You can't get more racist than that. And the court ignored that. It just said there's a reason for this and, we're going to defer to the state's articulation of that reason."

Demonstrators at the Supreme Court rally April 23 against a proposal to add a citizenship question in the 2020 census.

Irons says he doubts if any of those Supreme Court justices in that era experienced remorse over their decisions.

"They all came from white, privileged backgrounds," he says. "Their family status, their education -- they were part of the white elite."

Goldstone alludes to another part aspect of the Supreme Court that people often forget: The court's traditional role has been to block change , not affirm it.

"If you look at the history of this country from the first Supreme Court until now, for almost our entire history it has been conservative," Goldstone says. "It has been a protector of a certain status quo. It has certainly been protective of white rule."

It got away with protecting the status quo in the 19th century because not many white Americans cared if people of color like Plessy were treated like second-class citizens.

The court weighing the census decision is facing a much more diverse America. But that doesn't mean the conservative majority won't still try to tilt the court back to the 19th century, Goldstone says.

They would be fighting two powerful trends: A changing America and a court that has managed to put decisions like Plessy v. Ferguson behind it.

That would change if the court accepts the addition of a citizenship question to the census, Goldstone says.

"What we didn't do, other than the post-Reconstruction era, is really move backward," he says. "We kind of moved forward slowly. This could be the first time except for post-Reconstruction that the country really moved backward. It'll make us less free, less equal and less democratic."