U.S. President Donald Trump on December 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.
But as a practical matter, senators can declare their
allegiance before trial and cannot be disqualified for bias,
said Frank Bowman, an impeachment scholar at the University of
Missouri School of Law.
"You can imagine what a mess the trial would be if
disqualification motions would be entertained. Everybody would
be moving to disqualify everybody, and then the question would
be what body decides such a motion," Bowman said.
IS HEARSAY EVIDENCE ALLOWED?
U.S. law restricts what evidence is admissible in a criminal
case. The complex rules limit the use of "hearsay," or
secondhand information.
Such evidentiary rules do not apply to impeachment.
Republican lawmakers have criticized the House's impeachment
probe as a political exercise based on hearsay. They say
witnesses like former U.S. Ambassador to Ukraine Marie
Yovanovitch, who testified at House hearings, never spoke
directly to Trump and therefore lack credibility.
U.S. Chief Justice John Roberts could conceivably block
evidence from being used in the Senate trial on the grounds that
it is irrelevant or hearsay, but such a determination could be
overturned by a majority vote of the Senate, legal experts said.
Roberts does not want to be seen as partisan, so he will
likely "tread very carefully" and let senators make important
decisions, Bowman said.
WHAT IS THE STANDARD OF PROOF?
Jurors in criminal cases are instructed not to convict a
defendant unless there is proof of guilt beyond a reasonable
doubt.
There is no formal standard of proof in impeachment
proceedings, said Jessica Levinson, a professor at Loyola Law
School in Los Angeles.
"One would think there is an answer to this basic procedural
question, but there is not," Levinson said.
Jurors in criminal cases are asked to make factual
determinations, Bowman said. Senators, on the other hand, are
making both factual determinations and political judgments,
making it difficult to set a standard of proof, Bowman said.
HOW MANY SENATORS MUST VOTE TO CONVICT?
Under the U.S. Constitution, a two-thirds vote of the Senate
is required to convict the president. That differs from most
criminal trials, where juries must reach a unanimous verdict.