The Department of Justice (DOJ) and Attorney General William Barr did "exactly the right thing" in dropping charges against former Trump administration national security adviser Gen. Michael Flynn because there was never a crime committed, Harvard Law School Professor Emeritus Alan Dershowitz asserted Friday.

Flynn was exonerated by the DOJ on Thursday afternoon. The action comes even though prosecutors for the past three years have maintained that Flynn lied to the FBI in a January 2017 interview about his conversations with the Russian ambassador and following Flynn's own guilty plea.

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In a phone interview on the "Brian Kilmeade Show," Dershowitz said he feels that Barr probably cleared Flynn too late.

"In December of 2018, I wrote an op-ed piece saying there was no crime. Why? Because what he said -- what Flynn said -- was not material to the investigation for two reasons," he explained.

President Donald Trump's former National Security Advisor Michael Flynn arrives at federal court in Washington, Tuesday, Dec. 18, 2018. (AP Photo/Carolyn Kaster)

"Number one: the FBI already knew what the truth was," Dershowitz remarked. "They had him on tape. They had recorded him. talking to the ambassador [and] then they asked him, 'Did you talk to the ambassador?' They weren't looking for information. They were looking to spring a perjury trap."

Secondly, Dershowitz noted, newly released documents show FBI leaders including former Director James Comey and Deputy Director Andrew McCabe were looking into the Logan Act.

"They were investigating the Logan Act. Do you know what the Logan Act is? It was passed in the 18th century and it said private citizens can't negotiate with other governments," he stated.

"[Do] you know how many of our people have negotiated with other governments from Jimmy Carter when he told Yasser Arafat not to accept the Clinton peace deal to Jesse Jackson to [Dennis] Rodman the basketball player?" Dershowitz incredulously asked. "Nobody has been prosecuted under the Logan Act since 1803 and that prosecution failed and there's never been a successful prosecution. So, the entire enterprise was flawed.

"I called for the Justice Department to do this a year-and-a-half ago and they did absolutely the right thing," he told Brian Kilmeade. "Every civil libertarian should be rejoicing."

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Dershowitz lamented that the case has become a "right-left issue" when the real issue is civil liberty.

"But, every civil libertarian right or left should say, 'Finally, somebody is holding the government to what its proper role is' which is to get evidence of past crimes, not to create future crimes," he concluded.