WASHINGTON (Reuters) - What is bribery? The question was robustly debated by legal experts on Wednesday during a congressional hearing in the impeachment inquiry of U.S. President Donald Trump.

The back-and-forth highlights a dilemma faced by Democrats seeking to remove Republican Trump from office - whether to make “bribery” one of the formal charges or to use broader wording such as “abuse of power.”

The inquiry focuses on Trump’s requests that Ukraine conduct investigations that could benefit him politically and harm Democratic political rival Joe Biden, and $391 million in security aid to Ukraine that Democrats accuse Trump of using as leverage on a vulnerable U.S. ally.

“The bribe is to grant or withhold military assistance in return for a public statement of a fake investigation into the elections,” House of Representatives Speaker Nancy Pelosi said on Nov. 14. “That’s bribery.”

Trump has dismissed the impeachment inquiry as a partisan witch hunt.

There is an obvious appeal to framing Trump’s conduct as bribery, legal experts say: not only is it an easy concept to grasp, but it is one of the two impeachable offenses specifically mentioned in the U.S. Constitution. However, what exactly constitutes “bribery” in the impeachment context is not clear cut.

Wednesday’s debate in the House Judiciary Committee centered around two different approaches: The broad Constitutional view that the term encompasses efforts to trade official actions for private benefits, and the narrower modern-day definition used by federal prosecutors in criminal cases.

Pamela Karlan, one of three law professors called to the hearing by Democrats, said that she believed that the writers of the Constitution would have thought Trump’s actions rose to the level of bribery.

Karlan, a professor at Stanford Law School, said they understood bribery to encompass “when you took private benefits, or asked for private benefits, in return for an official act.”

In defining bribery for purposes of impeachment, Congress does not need to adhere to how that crime is defined under federal law, Karlan said.

“When they say explicitly in the Constitution that the president can be impeached and removed from office for bribery, they weren’t referring to a statute,” said Karlan.

But Jonathan Turley, a scholar chosen to testify by the Republicans, argued that Democrats should stick to a definition of bribery in the U.S. criminal code, which the U.S. Supreme Court said in a 2016 decision should be defined narrowly.

The Supreme Court has made clear that “it is a dangerous thing to take a crime like bribery and apply a boundless interpretation,” Turley said, adding “what I would caution the committee is that these crimes have meaning.”

Turley, a professor at George Washington University, also testified that in other modern impeachments of U.S. presidents, there was little debate that the alleged wrongdoing violated U.S. criminal laws.