Of the four charges included in the latest federal indictment of Donald Trump, one — violating Section 241 of Title 18 of the United States Code — seemed to surprise many. It shouldn’t have.

That statute dates back to Reconstruction, as Congress responded to the Confederacy’s white-power insurrection against the United States. Reconstruction sought not only to restore the Union after the Civil War, but also to build guardrails against such an authoritarian faction ever again being able to subvert the Republic.

It’s therefore appropriate that Section 241 and other Reconstruction-era laws are precisely those that the American legal system is turning to in response to a former president who stoked the flames of an insurrection in which a violent mob stormed the Capitol in an effort to undermine the democratic process. One of the rioters, later sentenced to three years in prison, carried a Confederate flag into the Capitol, an indelible image captured in photographs and widely circulated.

Congress enacted Section 241 as part of the Civil Rights Act of 1870 (also known as the Enforcement Act for its role in enforcing the terms of the 13th, 14th and 15th Amendments, crucial to providing Black people with the rights and protections of citizenship). The law addressed the rise of white supremacist groups after the Civil War, especially the Ku Klux Klan, which organized citizens and public officials to intimidate freed Black people to suppress their participation in the political process. It empowered federal agents to stop these conspirators from depriving any Americans, in particular Black Americans, of the right to have a say in their government.

The Justice Department has charged Mr. Trump with doing exactly that: the government asserts in its detailed 45-page indictment that through his attempts “to overturn the legitimate results of the 2020 presidential election,” Mr. Trump conspired to “injure, oppress, threaten and intimidate” voters in exercising their “right to vote, and to have one’s vote counted.”

Bringing civil rights charges against the former president is not overreach by the Justice Department, as some have suggested. By enforcing the Civil Rights Act of 1870, the department is doing the very thing the law was designed to do by prosecuting a political leader who, while in office and after, sought to cancel the votes of millions to hold power.

In 1871, with Klan violence continuing, Congress passed two more bills to enforce the 13th, 14th and 15th Amendments, known as the Ku Klux Klan acts. Among other things, these laws empowered citizens to sue anyone who conspired to intimidate or retaliate against them for exercising their political rights.

Armed with these laws, the Justice Department oversaw the arrest and conviction of hundreds of Klansmen, and by 1873 the group had been effectively (though temporarily) crushed. While Section 241 has regularly been used ever since to police civil rights violations, with the end of Reconstruction in 1877, Klan Act litigation brought by private parties declined precipitously, according to our research, until in recent years.

In July 2017, our organization, Protect Democracy, filed a Klan Act lawsuit against the 2016 Trump campaign over what we asserted was its role in Russian efforts to compromise the political rights of Americans. While that suit did not succeed, it was the beginning of a spate of private Klan Act litigation unseen in more than 100 years.

Several lawsuits have been filed by our group and others. Among the results: A restraining order was issued against armed groups that surrounded ballot drop boxes in ways that intimidated voters; the Proud Boys were ordered to pay more than $1 million in damages for desecrating the property of a Black church; and a jury ordered 17 white nationalist leaders and organizations to pay more than $26 million in damages to nine people who suffered physical or emotional injuries at the Charlottesville Unite the Right rally in 2017. Still pending are lawsuits seeking damages against those responsible for Jan. 6, against those who organized a car caravan that threatened to drive a campaign bus off the highway and against Mr. Trump and others for seeking to deprive Black voters from having their votes counted in the 2020 election.

Other Reconstruction-era laws are also in the center of debates today. Congress recently reformed the Electoral Count Act, passed in response to the contested presidential election of 1876, after Mr. Trump and his allies sought to use the law’s ambiguities to overturn the 2020 election. The former president has also pledged, if re-elected, to abolish the 14th Amendment’s guarantee of birthright citizenship. That guarantee was ratified in 1868 to reverse the Supreme Court’s Dred Scott decision holding that African Americans were not citizens.

Yet another 14th Amendment provision, Section 3’s prohibition on those who have engaged in insurrection against the United States from holding power again, was recently applied for the first time since Reconstruction to bar from office a New Mexico county commissioner who breached the barricades outside the Capitol on Jan. 6. And recently, our organization filed a voting rights lawsuit under the 1870 law that readmitted Virginia to the Union. The Virginia Readmission Act limited the circumstances in which the state could disenfranchise its citizens, and our lawsuit argues that the state’s lifetime ban on voting by anyone convicted of any felony violates that law.

These battles are the newest iterations of the Reconstruction-era clashes. Just as the integration of freed Black people into our democracy in the 1870s was met with fierce resistance, so too did the election of the nation’s first Black president give rise to a revival of open bigotry. And just as the enactment of laws in the 1870s to enforce equal citizenship were met with intransigence, so too today should we expect to see their enforcement resisted.

The outcome of these legal clashes will determine the future of the country’s experiment in self-government. Either these laws will finally be fully realized and usher in a true multiracial democracy or the 150-year resistance to Reconstruction will prevail and white Americans reluctant to share power will reinforce their dominance over a diversifying nation. Authoritarianism rather than democracy would then be the order of the day.

Ian Bassin is a co-founder and the executive director of the group Protect Democracy and a former associate White House counsel. Kristy Parker is counsel at Protect Democracy and the former deputy chief of the criminal section of the Justice Department’s Civil Rights Division.