U.S. President Donald Trump on Dec. 19 became the third U.S. president to be impeached when the Democratic-controlled House of Representatives voted to charge him with abuse of power and obstruction of Congress. The Republican-controlled Senate is due to weigh these charges in a trial in January.

In the unlikely event he is found guilty, Trump would be removed from office.

Trump and his Republican allies have attacked the impeachment effort as illegitimate, invoking concepts like “due process” and “hearsay” that are commonly associated with criminal cases.

While U.S. senators will serve as jurors, legal experts say an impeachment trial will look fundamentally different from a U.S. criminal proceeding. Here are the reasons why.

HOW DOES AN IMPEACHMENT TRIAL WORK?

In an impeachment probe, the House functions like a prosecutor’s office. If the chamber charges a president with committing impeachable offenses, a group of House members presents evidence of wrongdoing during a trial before the Senate, which acts as a jury in deciding whether the president should be removed from office.

Historically, presidents facing impeachment trials have been granted some protections like what defendants receive in criminal cases, such as the right to have a lawyer present and request witness testimony. But legal experts say impeachment proceedings were never intended to be conducted like criminal cases.

In a 1974 report, the House Judiciary Committee said impeachment was a remedial process, rather than punitive one.

“Impeachment and the criminal law serve fundamentally different purposes,” the report stated. “The purpose of impeachment is not personal punishment; its function is primarily to maintain constitutional government.”

DO SENATORS NEED TO BE IMPARTIAL?

U.S. judges are required to ensure that jurors are fair and do not prejudge a case.

Similarly, under the U.S. Constitution and Senate rules, senators take an oath and swear they will be impartial. Read more

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