What happens if a crime or even treason has been committed and those actions could reasonably be seen to have affected the result of the presidential election in November 2016?
There increasingly is a case to be made that Donald Trump's presidential campaign may have conspired, or attempted to conspire, with the Russian government or its agents to affect the result of 2016 election. It's still quite a stretch to prove at this point, but increasingly not beyond the realms of possibility. If senior members of the administration, including Trump family members, are found to have conspired with an "enemy" power to change the course of the Presidential election, then we are in completely uncharted territory.
The Constitution's Article II Section 4 provides that "The President, Vice President and all civil Officers of the United States, shall be removed from Office on Impeachment for, and Conviction of, Treason, Bribery, or other high Crimes and Misdemeanours." Treason is debatable but it would be hard to dispute that this isn't a "High Crime."
The impeachment process is an unusual one. The House of Representatives gets to impeach the President, which is essentially to indict him for the alleged offence, and then the Senate turns into a court to try the offence with the Supreme Court Chief Justice presiding. The Senate has to convict by a two-thirds majority. There have been three occasions that this extreme measure has been reached for. Twice, in the cases of Andrew Johnson and Bill Clinton, they were impeached, but in both cases the Senate failed to convict. Richard Nixon resigned before the process could fully swing into action, having seen the writing on the wall.
If an impeachment happened as a result of a conspiracy around the election, the Constitution has no provision for a re-run of the 2016 election or a mechanism to handover the Presidency to Hillary Clinton. The Founding Fathers obviously couldn't imagine that such a thing could happen.
Once a President is impeached, the rules of Presidential Succession would normally go into action. The rules and the order of succession have changed over the years, but first stop has always been the Vice President. An impeached President Trump would result in a new inaugurated President Pence, if the rules apply.
However, there would be a pretty large problem in this case. If the President resigns or is impeached because the election has been corrupted by his team, then replacing him with part of that team, which would have been so badly tainted, would cause consternation at the very least. The only remotely similar case is the departure of President Nixon, who was replaced by his Vice President, Gerald Ford. However, it is really important to remember that Ford wasn't elected Vice President but appointed to the role when Vice President Spiro Agnew had resigned due to tax problems. Gerald Ford had been ratified by Congress into his role and was a very well respected pair of "clean hands."
That leaves a political rather than a constitutional problem. Would anyone from Trump's world be acceptable given the upheaval that would have happened? Pence is a clever operator and has been very loyal so far, but will do everything he can to ensure that he isn't drawn into the whole mess. However, the all-consuming nature of Donald Trump is unlikely to leave him untarnished.
If the Vice President is disqualified, that leaves the next in line, the Speaker of the House. Now, this is where things could become interesting and timing is everything. The present Speaker is Republican Paul Ryan, who was Mitt Romney's running mate in 2012. Ryan is someone who would be a very acceptable to the mainstream of the Republican Party and is sufficiently out of Trump's orbit for the Democrats to agree to.
However, a lot depends on how long the whole process takes. There are mid-term elections due in November 2018, when the whole House is up for reelection. The party who doesn't hold the Presidency usually does well in mid-terms. A scandal-ridden Republican party would almost certainly lose seats and potentially lose control of the House. If that is the case, then the leader of the Democrats in the House becomes Speaker and would be directly in line to become President, if Trump and Pence go down.
Whilst the Republicans would fight with their last breath to stop it happening, there is a chance that the election of 2016 produces America's first female President, not Hillary Clinton but Nancy Pelosi. It might sound mad and far-fetched, but so did "President Trump," two years ago!
Mark Malcomson is Principal and CEO of City Lit. Mark also teaches American politics and is hosting a new course on 9 November about The US Presidents who made the post-war world at City Lit in Covent Garden.