The U.S. Department of Justice is dusting off a rarely used 1968 anti-crime measure known as the "H. Rap Brown Law" to launch prosecutions of both the far-left Antifa and white supremacists, DOJ sources told Newsmax on Tuesday.

Officially known as the Anti-Riot Act, the law makes it a federal crime to cross state lines "with intent (A) to incite a riot or (B) to organize, promote, encourage, participate in, or carry on a riot."

Sources in the prosecutorial community who spoke to us agreed the law would easily apply to Antifa after its role in the nationally watched (and often violent) demonstrations against the "Proud Boys" in Portland, Oregon, this weekend.

"An organization of terror," is what President Trump tweeted about Antifa, whose clashes with the "Proud Boys" brought Portland to a standstill this weekend.

Asked by Newsmax whether the "Brown Law" would be used against Antifa, a Justice Department spokesman had no comment.

But other sources within the DOJ pointed us to the U.S. Attorney's office in West Virginia, which has already used parts of the "Brown Law." This was in the successful prosecution of four California-based white supremacists for being part of a conspiracy to incite a riot at the August 2017 "Unite the Right" rally in Charlottesville, Virginia. (All three pled guilty and received prison sentences.)

Enacted as part of the 1968 Civil Rights Act, the measure also makes it a federal crime to use interstate commerce such as telephone, radio, or other forms of communications "with intent (A) to incite a riot or (B) to organize, promote, encourage, participate in, or carry on a riot."

The law is named after H. Rap Brown, world-famous black militant and leader of the Student Non-Violent Coordinating Committee (SNCC). Brown, who once said violence "was as American as cherry pie," was widely believed to have gone into various major cities to launch some of the major race riots of the 1960's.

(Having converted to Islam and changed his name to Jamil Abdullah Al-Amin, Brown, now 76, is currently serving a sentence for murder at the U.S. Penitentiary in Tucson, Arizona).

Most famously, the "Brown Law" was used to prosecute the "Chicago 7" defendants for crossing state lines to lead demonstrations at the 1968 Democratic National Convention. The "Chicago 7" were convicted Feb. 18, 1970, but their convictions were all overturned on appeal.

The "Brown Law" has since been used infrequently by prosecutors.

John Gizzi is chief political columnist and White House correspondent for Newsmax. For more of his reports, Go Here Now.