President Trump's granting of a full pardon to former Sheriff Joe Arpaio was seen by many legal experts as a sign of what may come in the special counsel's inquiry into Russia's meddling in last year's presidential race and possible collusion with the Trump campaign.
Trump has insisted the investigation led by former FBI Director Robert S. Mueller III is a "witch hunt" and should be shut down, the sooner the better. Some predict that the president will use his power to pardon anyone at any time for nearly any reason to make the investigation moot.
"Kim Jong Un was not the only leader testing his weapons" last week, said Bill Yeomans, a veteran Justice Department lawyer now working with the liberal Alliance for Justice, referring to the North Korean leader's missile launch a day after Trump pardoned Arpaio, the former sheriff of Maricopa County in Arizona.
"Trump launched a warning pardon that announced the weaponization of the pardon power," Yeomans said.
Trump insiders who might benefit include Jared Kushner, Donald Trump Jr., Paul Manafort, Michael Flynn and anyone else targeted by Mueller.
Former White House Counsel Bob Bauer agreed that the Arpaio pardon looked like "a test run for shutting down the investigation."
But a presidential pardon, sometimes described as a get-out-of-jail-free card, also comes with a lesser-known trade-off: Those receiving them are often no longer free to refuse to testify.
So long as they face an indictment or fear of federal charges, defendants or targets of an investigation may invoke their 5th Amendment right against self-incrimination. The Constitution says no one "shall be compelled in any criminal case to be a witness against himself."
But when charges or potential charges are wiped away by a presidential decree, so too is the right to refuse to testify before a grand jury or before Congress about what they know.
"As the Supreme Court put it in 1895, 'If the witness has already received a pardon, he cannot longer set up his privilege, since he stands with respect to the offense as if it had never been committed,'" said University of Texas law professor Steve Vladeck.
"Of course, that only works for federal offenses," Vladeck said. "The president can't pardon offenses against state law, and so theoretically, someone like Flynn or Manafort could still argue that they have a 5th Amendment right based upon potential state law crimes. That would, no doubt, provoke some pretty major litigation."
Still, the conflict between the president's pardon power and a defendant's right to remain silent could complicate any White House effort to thwart the investigation. Moreover, Trump could build a case of obstruction of justice against himself if he pardoned close associates who were under investigation.
And the president could even unwittingly help Mueller's team build a case against him. Freed from threat of prosecution and forced to testify, Trump's associates would face pressure to disclose everything they know, which could include damaging information about the president.
This is "difficult to game out," said Peter Zeidenberg, a Washington lawyer and former federal prosecutor. "Yes, witnesses who have been pardoned would lose their 5th Amendment privilege against self-incrimination and could therefore be forced to testify in the grand jury. If they lied, they would be subject to new charges of perjury or obstruction of justice. If they refused to testify, despite being granted immunity, they could be held in contempt. Of course, if that were to occur, Trump could just pardon them again."
"The bottom line is that if Trump is hell-bent on stymying this investigation by handing out pardons, he probably could do it," Zeidenberg said. "Of course he would then potentially be exposing himself to impeachment for obstructing the investigation into his own conduct."
Others said the president's willingness to use the pardon power could be enough to prevent his associates from cooperating with prosecutors. Rep. Adam B. Schiff (D-Burbank), the ranking Democrat on the House Intelligence Committee, tweeted that Trump's pardon of Arpaio "sends [a] message to witnesses in Russia investigation to keep quiet, stay loyal & get pardon."
The timing of pardons could be a critical factor.
"To be most effective, pardons should come late in the process," Yeomans said. For the defendant, "each lie to a federal investigator, grand jury or congressional committee is a new crime." A presidential pardon for past offenses does not entitle anyone to break the law in the future.
But Trump is not known for patience. He was not willing to wait months or years while Arpaio appealed his conviction for criminal contempt.
"He may be unable to control himself if it appears that indictments are imminent, particularly if they involve family," Yeomans said. "It is possible that he might try to act earlier in the process in the hope of impeding the investigation."
The scope of any pardon may also be important. If Trump granted a sweeping pardon that covered all possible federal crimes, the recipient would have a harder time trying to invoke his or her 5th Amendment rights than if Trump issued a narrower one, for a specific crime or indictment. A narrow or limited pardon may enable individuals to still refuse to testify by citing fear of other potential crimes that were not covered.
Trump's ultimate pardon power may rest with a question the nation has not yet confronted: Can a president pardon himself or herself?
Legal experts are divided, and the courts have not ruled. But the Constitution makes it clear that if a president is guilty of criminal conduct, the proper remedy is to seek his removal from office through impeachment.