"Mr. Trump’s musings on his planned prosecutions serve an immediate political purpose, highlighting his argument that his conviction in New York..."

"... was the product of an effort by Democrats to keep him from being elected again and providing the red meat of prospective retribution to his base. But they also have the effect, partly incidental and partly calculated, of undermining faith in the integrity of the criminal justice system, a development that could have profound effects in a nation where the rule of law has been foundational. Mr. Trump and his supporters have argued that the system is already politicized, pointing to the four criminal prosecutions against him as irrefutable evidence — an assertion rejected by those who say that no one, including a former president or leading presidential candidate, is above the law.... The president can certainly instruct his attorney general to investigate given individuals. In his 1960 presidential campaign, for instance, John F. Kennedy pledged to target Jimmy Hoffa, the labor leader.... "

Writes Adam Liptak, in "Trump’s Vows to Prosecute Rivals Put Rule of Law on the Ballot/Donald Trump’s promise to seek retribution challenges long-established norms. The election could hinge in part on what kind of justice system the country believes it has now and wants in the future" (NYT).

I think Trump's campaign rhetoric is mostly designed to force his adversaries to proclaim principles that support his own arguments. Liptak acknowledges that as he contends that what Trump is threatening to do to his political opponents is different from what they are doing to him. Trump's political enemies will appreciate the asserted difference. His supporters won't. And what is it? The most obvious difference is that Trump's opponents are currently deeply engaged in prosecuting him, but Trump did not prosecute his enemies in his first administration and he's only referring to the potential to do so the next time around. He's issuing a credible threat in a game of tit-for-tat that he did not start. Won't we need to see what charges his next administration brings (if there is to be a next administration)? These might be solid charges that rest on the proposition that no one is above the law... as Trump's opponents like to say about the charges brought against him.

Liptak quotes something Justice Alito said in the oral arguments in the case about presidential immunity:

"If an incumbent who loses a very close, hotly contested election knows that a real possibility after leaving office is not that the president is going to be able to go off into a peaceful retirement but that the president may be criminally prosecuted by a bitter political opponent, will that not lead us into a cycle that destabilizes the functioning of our country as a democracy? And we can look around the world and find countries where we have seen this process, where the loser gets thrown in jail.”

And Liptak follows that with this from lawprof Robert Gordon:

"A party may come into power determined to address injustices committed by the prior regime, as Argentina criminally charged leading generals after the dirty war, or Brazil is doing now against its former president. But the claims of injustices have to be true and their investigation and prosecution scrupulously fair. It’s pretty obvious... that turning law enforcement against your political opponents just to get revenge on them is among the worst crimes a regime can commit."

Just to get revenge.... Trump isn't threatening to do this just to get revenge... or even to get revenge at all. He is saying that there is profound corruption and that a "terrible precedent" has been set. He wouldn't be starting the "cycle that destabilizes the functioning of our country as a democracy." I don't know that he plans to continue it or accelerate it, but I do think he believes that he needs to confront his opponents with what they have done.

Here's how Trump put it in the interview with Sean Hannity that aired last night. He was asked whether he would keep the cycle going and prosecute his political adversaries. He said:

"Look, what's happened to me has never happened before.... It has to stop, because otherwise, we're not going to have a country. Look, when this election is over, based on what they've done, I would have every right to go after them, and it's easy, because it's Joe Biden and you see all the criminality, all of the money that's going into the family and him, all of this money from China, from Russia, from Ukraine...."