Trump impeachment trial 'will be quick'
Prof Ilya Somin, of George Mason University School of Law, says Donald Trump's impeachment trial will happen quickly because Republicans and Democrats want the process to run speedily.
But it is still unclear whether witnesses would be called.
He told BBC World News legality was only one part of an impeachment trial.
The political element was "as much or more important".
So President Trump "may well get off simply based on partisan politics and the fact that you need an overwhelming, two-thirds majority".