Four rules senators should follow during Trump's impeachment trial

US senators are expected to hear opening statements next week in the impeachment trial on whether to remove President Donald Trump from office on charges he abused his powers and obstructed a congressional inquiry into his effort to pressure Ukraine to investigate Democratic presidential contender Joe Biden.

Upon the arrival of Chief Justice John Roberts, who will preside over the trial, the senators are expected to silently stand until Roberts takes his seat.

Here are four rules on behaviour during the third impeachment trial in US history as outlined in a Senate memo:

* No live-tweeting. Cell phones and other electronic devices should be left outside.

* No outside reading material. Only documents related to impeachment should be brought into the Senate chamber.

* No talking. Senators should refrain from speaking to their neighbours while the case is presented.

* Hit pause on presidential campaigns. Senators should plan to be in attendance at all times during the proceedings. Democratic senators Elizabeth Warren, Bernie Sanders, Amy Klobuchar and Michael Bennet will have to leave the campaign trail and return to Washington.