What is obstruction of justice, and could it apply to Trump?

— -- Amid searing reports that President Donald Trump asked then-FBI Director James Comey to drop the agency’s investigation into his former national security adviser Michael Flynn, questions are being raised about whether the president obstructed justice.

According to a report Wednesday in the Washington Post, special counsel Robert Mueller is now examining whether Trump did in fact obstruct justice - or tried to do so.

After the story was published, Mark Corallo, a spokesman for Trump's attorney, Marc Kasowitz, issued a statement addressing only what he referred to as a "leak" from the FBI.

“The FBI leak of information regarding the president is outrageous, inexcusable and illegal,” Corallo said.

Special counsel spokesman Peter Carr would offer no comment to ABC News about the report.

Comey testified earlier this month about his interactions with Trump, detailing their various meetings before he was fired in May. In his prepared opening statement to the Senate Intelligence Committee hearing, Comey wrote that Trump told him, “I hope you can see your way clear to letting this go, to letting Flynn go.”

Comey allegedly included a similar account in a memo he wrote immediately following that meeting with Trump.

Comey went on to share the memo with top FBI associates before he was fired.

ABC News has not seen the memo.

What is obstruction of justice?

Obstruction of justice is a federal crime in which someone "corruptly" attempts to “influence, obstruct or impede” the “due and proper administration of the law” in a pending proceeding, as stated in 18 U.S.Code § 1505.

“Corruptly” is defined in an accompanying section, 18 U.S.Code § 1515 (b), as “acting with an improper purpose, personally or by influencing another, including making a false or misleading statement, or withholding, concealing, altering, or destroying a document or other information."

Liza Goitein, a former trial attorney for the U.S. Department of Justice who currently co-directs the Liberty and National Security Program at the Brennan Center for Justice at New York University Law School, put the statute in simpler terms.

“To boil this down, if the president corruptly attempted to influence the due administration of justice, that is obstruction of justice under the statute,” Goitein told ABC News. “This is an incredibly serious offense.”

If Comey's testimony and the alleged contents of his memo are accurate, does that meet the definition of obstruction of justice?

Legal experts are mixed.

“This looks very much like obstruction of justice,” Goitein told ABC News in reference to Comey’s memos. “It’s hard to reach a different conclusion. It is certainly possible that he incorrectly remembered the conversation or misrepresented it. But there’s no reason to think that’s the case.”

David Shapiro, a former FBI special agent and now an assistant professor at John Jay College of Criminal Justice, told ABC News, "It's hard to view this as anything other than obstruction of justice.”

Laurence Tribe, professor of constitutional law at Harvard Law School, told ABC News that if Comey’s memo is accurately reported, then he believes it describes “an impeachable attempt to obstruct justice.”

John Lauro, a defense attorney with the Lauro Law Firm based in Tampa and New York City, told ABC News it remains unclear whether Trump obstructed justice.

"It depends on the evidence, which right now amounts to triple and quadruple hearsay," Lauro said. "If Comey felt there was obstruction he would have been obligated to advise the Attorney General and formally open an investigation, none of which appears to have happened."

David McIntosh, a lawyer and former congressman who is now the co-founder of the Federalist Society for Law and Public Policy Studies in Washington, D.C., defended Trump, saying the president "acted appropriately" if he was providing guidance to Comey on the investigation.

"It is important for us to step back and remember that, under the Constitution, the president has the authority and power to enforce the laws," McIntosh said at a press conference Wednesday morning. "The FBI director reports to the president and it is the president's decision to delegate authority on investigations. In delegating that authority, presidents have wisely chosen to insulate the FBI from political interference. But the president still has the power and authority to direct the FBI how to do their job."

What is Mueller's role in the investigation?

Mueller, Comey's predecessor as FBI director, was appointed special counsel by Deputy Attorney General Rod Rosenstein.

On May 17, Mueller was tapped to investigate Russian interference in last year's presidential election and whether any close associates of the president colluded with Russian officials.

In a statement Rosenstein said, "My decision is not a finding that crimes have been committed or that any prosecution is warranted. I have made no such determination. What I have determined is that based upon the unique circumstances, the public interest requires me to place this investigation under the authority of a person who exercises a degree of independence from the normal chain of command."

As special counsel, Mueller has independent authority to exercise all investigative and prosecutorial functions of a United States attorney. He can take matters before a grand jury, issue subpoenas and assign federal agents to the case.

"If the Special Counsel believes it is necessary and appropriate, the Special Counsel is authorized to prosecute federal crimes arising from the investigation of these matters," Rosenstein wrote in his May 17 letter announcing Mueller's appointment.

What are the potential legal ramifications?

Congress can take more formal steps to look into whether Trump’s actions amount to obstruction of justice, and the legislative body can issue a subpoena to obtain Comey's memo as evidence if necessary, according to ranking member of the House Intelligence Committee Rep. Adam Schiff.

Schiff said that Congress may be preparing to do so.

"Congress will need to subpoena them if indeed they're not provided voluntarily. I certainly support that. I think there are many committees that will," Schiff, D-Calif., told ABC News chief anchor George Stephanopoulos on May 17.

Legal experts said Congress can also subpoena other documented communications between Comey and Trump, including any recorded conversations or meetings.

"The key evidence is the notes that Comey took,” Shapiro told ABC News. "Corrupt intent is required to prove obstruction of justice. Comey's firing fits into the greater picture there."

Legal experts said obstruction of justice, if proven to be true, is a high crime and could be an impeachable offense.

Impeachment is a political process in which any civil officer, including a president and vice president, can be removed from office “for, and conviction of, treason, bribery, or other high crimes and misdemeanors,” according to the Article II, Section 4 of the U.S. Constitution.

New York-based criminal defense lawyer Ronald Kuby told ABC News there is no definition of "high crimes and misdemeanors," but rather "it's whatever Congress thinks it should."

The House of Representatives wields the sole power to impeach a federal official, and the Senate has the sole power to convict and remove the individual.

The House needs a simple majority vote to approve an article of impeachment, which can be brought by any member. If the House votes to impeach an official, the case must then be presented to the Senate, which will hold a trial. The Senate needs a two-thirds majority to find the official guilty and remove him or her from office.

Ultimately, some legal experts said, it’s unrealistic to expect the Justice Department to file criminal charges against Trump -- and it might not be legally possible. Impeachment would be the only process through which a charge of obstruction of justice could realistically be brought against Trump, experts noted.

“No sitting president has ever been prosecuted for any crime,” Goitein told ABC News. “So that seems unlikely.”

ABC News' Jack Date, Lauren Pearle, Kate Shaw, Benjamin Siegel, Pierre Thomas and Cecilia Vega contributed to this report.