The original decree was issued in 1982 by the Federal District Court in New Jersey after the R.N.C. allegedly tried to intimidate registered voters in black communities by, among other things, hiring off-duty sheriffs and police officers to stand at polling places displaying their guns and armbands that said “National Ballot Security Task Force.” It barred the national committee and its “agents” from “ballot security activities” that deter qualified minority voters from voting, whether intentionally or not.

In 1987, the court extended the decree, which applies nationwide, after allegations that R.N.C. officials created a voter-challenge list in Louisiana to, as one internal memo put it, “keep the black vote down considerably.” It also required the national committee to get judicial approval before organizing or directing any poll-watching activities. In 2009, following several other episodes of alleged minority-voter intimidation involving the R.N.C., the decree was again extended for eight years.

In other words, Donald Trump’s abhorrent efforts to keep black and other minority citizens from voting are only the latest example of a long-running Republican strategy. Unsurprisingly, the man behind the New Jersey voter-intimidation case that led to the original decree, Roger Stone, is now one of Mr. Trump’s top advisers. On Oct. 23, Mr. Stone, who has updated his bag of dirty tricks for the digital era, sent a now-deleted tweet intended to mislead Hillary Clinton supporters by encouraging them to “vote the new way” — by text message.

The R.N.C. says it does not condone this sort of behavior, and it recently warned its members not to violate the decree. At the same time, the committee’s chairman, Reince Priebus, said earlier this month, “I want to make it very clear that the R.N.C. is in full coordination with the Trump campaign,” and that “we remain very much involved and together in all levels in making these decisions of how best to run the operation across the country.”

Of course, the claims of voter fraud are themselves fraudulent; in-person voter fraud essentially never happens, as study after study has confirmed. As the federal court in New Jersey said in 2009, voter intimidation of the type the Trump campaign is now encouraging, and in which the R.N.C. has engaged, “presents an ongoing threat to the participation of minority individuals in the political process, and continues to pose a far greater danger to the integrity of that process than the type of voter fraud the R.N.C. is prevented from addressing by the decree.”