Attorney General Jeff Sessions has taken a VERY weak position on Hillary Clinton crimes (where are E-mails & DNC server) & Intel leakers! — Donald J. Trump (@realDonaldTrump) July 25, 2017

As it has turned out, James Comey lied and leaked and totally protected Hillary Clinton. He was the best thing that ever happened to her! — Donald J. Trump (@realDonaldTrump) October 18, 2017

Other aspects of Mueller's obstruction probe include the president's questioning of key witnesses about what they discussed with investigators, misleading official White House news releases and the reported consideration of pardon offers to targets of the investigation who might choose to cooperate with Mueller. Mueller is reportedly looking into whether these actions add up to witness intimidation. The New York Times reports that Rudolph Giuliani, Trump's lead lawyer, has rejected the interest in the president's tweets as desperation. "If you're going to obstruct justice, you do it quietly and secretly, not in public," Giuliani told the publication.

"There's rarely evidence that someone sits down and says, 'I intend to commit a crime,' so any type of investigation hangs on using additional evidence to build a narrative arc that hangs together," Samuel Buell, a Duke University law professor and former senior federal prosecutor, told the New York Times. "That's why a prosecutor wants more pieces of evidence. You need to lock down the argument."

Another legal issue surrounding Trump's tweets has to do with his tendency to block other users, namely critics. Because he uses his personal account to discuss matters of national interest, many have argued that the account constitutes an official communication and one that anyone should be allowed to read. In May, a federal judge agreed, saying the president shouldn't be allowed to block users as it's a violation of the First Amendment. Last month, the US Department of Justice announced that it would be appeal the ruling.