Share U.S. Donald Trump Impeachment Robert Mueller Russia investigation Lawyers supporting President Donald Trump argued Monday that he cannot be charged with obstruction of justice. Yet legal experts say charging him is not necessary to bring articles of impeachment against the commander-in-chief. Lawyers supporting President Donald Trump argued Monday that the president cannot be charged with obstruction of justice. Their comments followed a potentially incriminating Twitter message about former national security adviser Michael Flynn sent from Trump’s social media account on the weekend that implied the president might have known Flynn lied to the FBI. On Sunday Trump’s lawyer John Dowd took the blame for the tweet, which suggested Trump knew Flynn lied to the FBI before the president allegedly urged former FBI Director James Comey to stop investigating Flynn. Trump denies having asked Comey to stop investigating Flynn. Keep up with this story and more by subscribing now Allegations of obstruction of justice also surrounded Trump's firing of Comey in May. Under the constitution, Trump has the authority to fire the FBI director at a moment’s notice. However, shortly after firing Comey on May 9, Trump justified the move in an interview with NBC News, referring to the FBI's Russia probe: “I said to myself, I said you know, this Russia thing with Trump and Russia is a made-up story.” U.S. President Donald Trump calls on a reporter for a question as he departs for travel to Utah from the White House in Washington, U.S. December 4, 2017. Jonathan Ernst/Reuters "You cannot charge a president with obstruction of justice for exercising his constitutional power to fire Comey and his constitutional authority to tell the justice department to who to investigate and who not to investigate,” argued Harvard law professor Alan Dershowitz on Fox & Friends Monday. "You need clearly illegal acts” to pin down a president with an obstruction of justice charge Dershowitz said. “With Nixon, hush money paid, telling people to lie, destroying evidence. Even with Clinton they said that he tried to influence potential witnesses not to tell the truth. But there has never been a