In October of 2019, the House of Representatives formally announced an impeachment inquiry into President Donald Trump. The impeachment investigation and hearings lasted until December, at which point the House of Representatives took a formal vote to impeach Trump. 

Trump was impeached on charges of abuse of power and obstruction of Congress, making him the 3rd President in U.S. history to be impeached, along with Andrew Johnson and Bill Clinton. There was a delay to the start of the trial as the rules were negotiated.

In January, the articles of impeachment were officially passed to the Senate and the trial began. The trial will have one of two outcomes — either Trump will be found guilty and removed from office or he will be acquitted. If Trump is acquitted, he will continue the rest of his term. If he is convicted, Vice-President Mike Pence will be sworn in to finish out Trump’s term before the next election. 

The trial will involve evidence and witnesses presented by both sides. Senators are required to attend the trial every day except Sunday until the trial concludes. Once all the evidence has been presented, the senators will have one day to consider their decision before being asked to take a vote. The length of the trial will depend on the amount of evidence presented and the time it takes. 

For Trump to be convicted, the Senate would need to a ⅔ majority vote to find him guilty. For Trump to be acquitted, the Senate would need a vote with a slimmer majority finding him guilty or a majority finding him not-guilty. 

The Republican Party holds a 57 member majority in the 100 person Senate, leading to concerns that the trial will be influenced by partisan alliances. Similar concerns were raised about the Democrat majority House during the impeachment inquiry. 

The trial is being presided over by Supreme Court Chief Justice John Roberts.