Trump federal indictment: How serious are obstruction charges?

Of all of the federal charges that former president Donald Trump and his aide Waltine Nauta face in the investigation into the alleged mishandling of top secret government documents, obstruction is one of the most serious, according to legal experts.

Claire Finkelstein, the founder and faculty director of the Center for Ethics and the Rule of Law (CERL), at the University of Pennsylvania’s Annenberg Public Policy Center, noted that the obstruction charges in the indictment against Trump and his aide carry as much serious weight as the charges related to keeping the top secret documents, with a maximum penalty of 20 years in prison.

Finkelstein told ABC News this was not surprising, as the federal government has always treated allegations of interfering with any investigation seriously and often spearhead these kind of probes.

"You can see it as the most important charges, as protecting the rule of law goes," she said.

Finkelstein said an obstruction charge can cover a broad range of alleged activities from as simple as lying to investigators to as major as destroying evidence. But it all comes down to one clear allegation, she said: That the accused deliberately interfered with an ongoing criminal investigation.

"[U.S. Code] 1001 is lying to investigators. Very, very often you find 1001 charges filed in federal court," she said.

Vida Johnson, an associate professor of law, at Georgetown University, told ABC News that federal prosecutors will seek an indictment on obstruction when they have evidence the subject knows they are part of an investigation.

"This is sort of the classic type of crime where people say the cover-up is worse than the crime," she said. "The idea that you would cover up, that is the type of thing that prosecutors always look for."

The federal government issued six counts related to obstruction against the former president and his aide.

Trump allegedly ordered Nauta, his attorneys and other staff members to move boxes of government documents, some of which included nuclear information and information regarding other nations, to his Mar-a-Lago estate after leaving office, according to the federal indictment. The boxes were allegedly kept in disarray in unsecured locations including a ballroom and bathroom, according to investigators.

After he was subpoenaed, Trump allegedly had his attorneys falsely sign an affidavit that all of the documents were returned, according to federal prosecutors.

Trump, who is scheduled to be arraigned Tuesday in Miami, has repeatedly denied any wrongdoing and accused federal prosecutors of a political "witch hunt."

"We did absolutely nothing wrong. ... It's a disgrace what's happening," he said at a campaign event on Saturday.

Finkelstein noted that obstruction can be charged against individuals who aren't the main focus of a federal investigation.

"Even if you were a bystander and saw something like documents being taken away, if you deliberately lie to investigators, you're liable," she said.

Nauta allegedly lied to investigators when he denied having knowledge about the location and movement of the documents before Trump provided them to authorities even though there were alleged communications between himself, Trump and other staffers about previously moving the boxes of documents, the indictment said.

Trump has defended Nauta and the aide accompanied the former president during campaign events over the weekend.

Finkelstein said that prosecutors tend to gather as much evidence as possible to make a strong case before a grand jury and trial jury. Finkelstein said Special Counselor Jack Smith and his team would be very thorough given this is a major investigation that concerns national security and a former head of state.

Trump's indictment references recorded conversations where he allegedly admits to knowing the documents at Mar-a-Lago were classified, text messages about the alleged movement of the documents and testimony from witnesses.

Finkelstein said the government will stress their obstruction case is based on the fundamental idea that no one is above the law.

"If the government can't rectify those basic rule of law violations, or wrongdoings…then we have damaged quite a profound component of the rule of law," Finkelstein said.