Not content with trying to destroy America’s trust in the US election system with his big lie that the 2020 presidential election was stolen from him, Donald Trump is now trying to destroy America’s trust in the US judicial system with another big lie.

The second big lie is that judges, prosecutors, witnesses and juries are corruptly prosecuting Trump as a means of keeping him from being re-elected.

Late on Monday, following a two-and-a-half-year investigation by the Fulton county, Georgia, district attorney, Fani Willis, a grand jury there charged the former president and 18 others with criminally seeking to overturn Joe Biden’s 2020 victory in Georgia.

This fourth indictment marks another step in the US’s slow but steady process of criminal justice. It is another illustration that no one is above the law.

Willis and her staff deserve the nation’s thanks, as do special counsel Jack Smith and his staff at the justice department, who have brought evidence to other grand juries of Trump’s efforts to overturn the results of the 2020 election nationwide and to steal secret documents.

None of this is easy work under the best of circumstances. With a rogue former president fanning the flames of anger and recrimination, the work is also potentially dangerous.

Trump has called Willis “corrupt”, and worse. He has called Smith “deranged”, among many other epithets and baseless charges. He has leveled similar charges against judges who have already been assigned to hear the cases against him.

We know all too well of the violent proclivities of a subset of Trump supporters. His wild statements endanger people. Willis and her staff have already been threatened, as has Smith, and potential witnesses.

On Monday morning, for example, before the Georgia grand jury even met, Trump posted that he “had been reading reports” that former Georgia lieutenant governor Jeff Duncan would be testifying before the grand jury.

Trump then charged that Duncan “was, right from the beginning of this Witch Hunt, a nasty disaster for those looking into the Election Fraud that took place in Georgia. He refused having a Special Session to find out what went on … and fought the TRUTH all the way.”

Was Duncan intimidated by Trump’s post when he testified on Monday? Did he alter or downplay his testimony out of fear of retribution by a Trump supporter?

We may never know. But the mere possibility of intimidation is itself troubling.

Trump’s conditions of release at his arraignment in Washington earlier this month included a vow – which Trump swore to uphold – that he would not intimidate or harass witnesses and officers of the court or threaten the administration of justice.

Yet Trump has not ceased posting inflammatory invective against potential witnesses, against potential jurors in Washington DC, New York and Georgia, against judges who have been assigned to hear the cases against him, and against Willis, Smith and other prosecutors.

The possibility that his threats might silence potential witnesses, or that his rants might intimidate jurors, prosecutors and judges, cannot be dismissed. It is incumbent on the courts to stop Trump, even if it requires revoking his release from jail pending his trials.

Trump’s invective is also having a more insidious effect. By casting the criminal justice system as corrupt and partisan – as part of a conspiracy to prevent him from being re-elected – Trump is undermining public trust in that system.

Republican members of Congress have joined Trump in charging that Democrats have “weaponized” the prosecutions against him, even though those prosecutions come through grand juries composed of average citizens.

More than half of Republicans – including 77% of self-identified Maga Republicans – say the indictments and investigations against Trump are an attack on people like them, according to a CBS News/YouGov poll taken soon after the most recent indictment.

“I AM BEING ARRESTED FOR YOU,” Trump posted in all caps on 3 August, the day of his indictment in Washington for seeking to overthrow the 2020 election.

“I’m being indicted for you,” Trump said in June, after being charged with retaining government secrets.

A century ago, the world witnessed fascist leaders who sought to fuse their identities with their followers while sowing distrust in all other institutions, so that followers lost their capacities for independent thought and accepted whatever the leaders said as truth.

If a substantial portion of the American public comes to believe that the judges, juries and prosecutors seeking to hold Trump accountable for trying to overturn the 2020 election are part of the same trumped-up plot to keep him from becoming president, the US’s 244-year experiment in self-government is seriously jeopardized.

Trump’s second big lie is almost as dangerous to the future of American democracy, and to the rest of the world that looks to the US for leadership, as was his first.

The second big lie should be understood as an extension of Trump’s attempted coup.

• Robert Reich, a former US secretary of labor, is professor of public policy at the University of California, Berkeley, and the author of Saving Capitalism: For the Many, Not the Few and The Common Good. His new book, The System: Who Rigged It, How We Fix It, is out now. He is a Guardian US columnist. His newsletter is at robertreich.substack.com