President Donald Trump’s lawyer, Marc Kasowitz, is considering whether to file a complaint against former FBI Director James Comey over his testimony that he shared a memo with his friend last month outlining his conversations with Trump about former national security adviser Michael Flynn.

That friend, Columbia law professor Daniel Richman, gave the memo to the New York Times at Comey’s instruction after Trump implied that there may be tapes of their conversations, Comey told the Senate Intelligence Committee on Thursday.

“My judgment was, I need to get that out into the public square,” Comey said. “I asked a friend of mine to share the content of the memo with a reporter. Didn’t do it myself for a variety of reasons. I asked him to because I thought that might prompt the appointment of a special counsel.”

In a statement later, Kasowitz called Comey’s decision to share the memo with someone outside the Department of Justice “an unauthorised disclosure of privileged information.”

“We will leave it the appropriate authorities to determine whether this leaks should be investigated along with all those others being investigated,” Kasowitz said.

But legal experts broadly agree that Comey’s disclosure of the memo did not constitute a “leak” because it did not contain classified information, and he was a private citizen when he shared it.

“Executive privilege almost certainly does not cover the Comey memo,” Steve Vladeck, a professor of law at the University of Texas School of Law specializing in national security, wrote on Friday. “And even if it did, disclosing it without authorization isn’t illegal.”

Vladeck said executive privilege is meant to be used as a defence, not a weapon, and to protect government officials from being forced to share internal White House communications with outside entities. But officials who want to share those communications can’t be stopped by an invocation of executive privilege alone.

“This is why Trump could not have invoked executive privilege to stop Comey from testifying, something the White House tried not to acknowledge by putting out word that he ‘chose’ not to do so,” Vladeck wrote. “It is not a ‘violation’ of executive privilege to voluntarily disclose materials that could be protected by the privilege, no matter what Kasowitz says.”

It’s also not illegal, as long as the information Comey shared wasn’t related to “the national defence” or anything financially valuable.

“It’s hard to see how Comey’s after-the-fact transcription of his relevant conversations with the president fall within either of these provisions,” Vladeck said. “No one is making an argument that the material in Comey’s memos was classified, or that information about a conversation could have the kind of monetary value required to trigger the federal conversion statute.”

David Cole, the national legal director of the ACLU, agreed.

“It’s not a leak,” he said on Friday. “The material was not classified.”

Additionally, said former DOJ spokesman Matthew Miller, Comey wasn’t acting as Trump’s attorney, so there was “no attorney-client privilege.”

It’s a “frivolous distraction,” Miller said, adding that there was “no violation” of Department of Justice rules in Comey sharing his memo with someone outside the department.

Vladeck noted that just because what Comey did wasn’t explicitly illegal doesn’t mean it was appropriate.

“Not for the first time, it appears that Comey took it upon himself to breach important norms governing the conduct of senior law enforcement officials — an offence that, perhaps ironically, would have unquestionably justified his termination, if he hadn’t already been fired before doing it.”

Scott Olson, a recently retired FBI agent who specialised in counterintelligence and spent more than 20 years at the bureau, pointed out that Comey himself probably would have fired “anyone who leaked notes or revealed the contents of conversations.”

“It is now clear that throughout all of these events, Comey has protected himself first and foremost,” Olson said. “And he has done it under a facade of upright moral intent. He’s a huge disappointment.”

Comey has been criticised in the past for his tendency to sidestep the Department of Justice in what he has characterised as attempts to protect the FBI’s reputation — whether it was closing the Hillary Clinton email investigation himself in an unprecedented press conference last July, or sharing Trump-related memos with the press, Comey has consistently defended his decisions by saying he always acted in the bureau’s, and the nation’s, best interest.

But many saw Comey’s frequent departures from protocol as a sign that he was unpredictable or untrustworthy.

“What really leaps off the page is the pervasive lack of trust between everyone involved here,” Olson said, referring to Comey’s written testimony about his interactions with Trump before he was fired in early May.

“Trump asks for a loyalty pledge because he doesn’t trust Comey and Comey documents everything in memos because he doesn’t trust Trump,” Olson said. “In addition, Comey doesn’t trust [Attorney General] Sessions will believe him without independent corroboration so he intentionally keeps Sessions in the dark about an Oval Office conversation which Sessions absolutely needed to know about. And most tragically, Comey doesn’t trust anyone other than himself to do the right thing.”

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