When Donald Trump fired James Comey, the man who was investigating the links between the Trump election campaign and the Russian government, many were drawn to the comparison with Richard Nixon's 'Saturday Night Massacre', where Nixon had attempted to forestall investigation of his role in the Watergate break in by firing an independent special prosecutor in charge of the investigation. The attempt led to the resignation of the Attorney General and Deputy Attorney General and, eventually, to Nixon's resignation in the face of imminent impeachment.

From the moment he was elected predictions has been rife as with no previous President that Donald Trump would not make it to the end of his first term, with possible impeachment being one method to remove him. After the firing of Comey the odds on Trump being impeached (as offered by UK bookmakers) have dropped considerably.

Specific crimes or misdemeanours need to have been committed to trigger any impeachment process. However, a vital issue here is that impeacment is not a legal process, triggered by the commission of a crime and followed up by the justice system, it is a political one and can only be triggered by Congress. With both houses of Congress controlled by the Republicans, it woud rely on a decision by the Republcan party that it could no longer deal with Trump in the White House (and that it could stomach the blow to the credibility of the party that would come from having one of its Presidents impeached). If the former is believable, given the oppostition to Trump by much of the party during the Presidential primaries, the latter is ore challenging. Nixon was nearly impeached by a Democrat controlled Congress, Clinton by a Congress split between the Republicans and Demorats. Would the Republican House of Representatives and Senate really vote to remove its own President? Signifiantly, no President has ever been impeached (Nixon resigned before he could be impeached and was later pardoned by his successor, Gerald Ford).

It should be noted that, after the Saturday Night massacre, it was still another 900 days before Nixon was forced to resign. Perhaps impeachment might be ont the cards one day, but will Trump be able to make it to the end of term on, or even two, before that comes?