Trump believes Bill Barr and Brett Kavanaugh will help him win every lawsuit: Former associates

President Donald Trump is relying on familiar tactics to battle a slew of investigations into his administration, his campaign and his family's business -- but now he has reason to believe he's successfully stacked the deck in his favor.

The 72-year-old Trump has sued or been sued at least 4,000 times, and he's relying on tactics he learned from his longtime fixer Roy Cohn to block or stall investigations of his finances, and these lawsuits are testing the limits of the constitutional separation of powers, reported Politico.

“He sues,” said Barbara Res, a former Trump Organization executive vice president. “That’s his M.O. He sues.”

Jack O'Donnell, former president of the Trump Plaza casino in Atlantic City, New Jersey, said his former boss uses lawsuits to wear people out financially and emotionally, and Trump biographer Tim O'Brien knows what it's like to be on the receiving end of a Trump lawsuit.

“He’s used litigation historically to keep hostile forces at bay and to delay reckonings,” O’Brien said. “He’s also used it to try to embarrass competitors, critics or opponents, and I think by and large he’s done that successfully. He’s the poster child for the abuses and inefficiencies of the American court system.”

But those tried-and-true tactics are testing the U.S. legal systems in new, and potentially dangerous, ways now that Trump is president.

"That is the question that’s being tested right now," O'Brien said. "Is Donald Trump, as president, above the law?”

Although Trump is enduring more scrutiny than ever before, he's now the most powerful man in the world -- and the Republican-controlled Senate has helped him stack the court system in his favor, and Attorney General William Barr has turned the Justice Department into a shield for the president.

“I think he expects that the judges he appoints will help him one day,” said Michael D’Antonio, a Trump biographer and CNN analyst.

Res, who was project manager for the construction of Trump Tower, said the president understands the powers he now has.

“I think he believes that every suit he’s involved in will go to the Supreme Court and he will win,” Res said.

“Because he’s got the deck stacked,” O’Donnell agreed.

“I think," O'Brien added, "unless institutions, particularly the law enforcement community and Congress, stand up for the rule of law, Trump is going to do an end-run around people.”