Covington & Burling offices in Washington, D.C. Credit: Diego M. Radzinschi / ALM

In the past week, as Covington & Burling scrambled to ensure the entire case file of its former client Michael Flynn had been turned over to his new lawyer, the law firm bristled at what it considered an unreasonable request from the former Trump national security adviser.

On Monday, Covington said in a court filing that Flynn's new lawyer, Sidney Powell, had called on the firm to go beyond the case file and conduct a more expansive search encompassing "every communication of any kind, including telephone records of every call, of every Covington employee, in which the Flynn case is mentioned." It was a position "strikingly different from the well-recognized obligation of a law firm to turn over the client file to successor counsel," the Covington lawyers said.

"To accept successor counsel's interpretation would require Covington to conduct a massive sweep of its servers for every document and communication pertaining to the firm's representation of Mr. Flynn, extending to every instance where any firm lawyer made any comment about the firm's high-profile representation of Mr. Flynn," the former defense lawyers at the firm, including Covington partner Robert Kelner, said in the new filing. "That would be a disproportionately burdensome e-discovery process of great scale and duration."

Covington's filing revealed only the latest point of tension between the firm and Flynn, who pleaded guilty in December 2017 to lying to federal agents about his contacts with the Russian ambassador to the U.S. in the run-up to Trump's inauguration. Flynn cooperated for months with the special counsel investigation and even repeated his guilty plea in court before abruptly dropping his Covington defense team last year and hiring Powell.

The maneuvering portended his bid to convince a judge to dismiss the case or, in the alternative, to rescind his admission of wrongdoing.

On Twitter, Powell contested the claim that she was asking the firm to conduct an overly broad search for Flynn records. Powell, a former federal prosecutor known more recently for railing against the Russia investigation on Fox News, said she wanted the firm's search to include the telephone records "specifically" of two high-profile Covington lawyers: former U.S. Attorney General Eric Holder Jr., who led the Justice Department under the Obama administration, and Michael Chertoff, a former secretary of homeland security. Neither lawyer represented Flynn.

A Covington spokesperson declined to comment. Powell pointed to her tweets when asked for comment.

Flynn's months-long campaign has featured accusations of prosecutorial misconduct and claims that Covington provided him with ineffective counsel. U.S. District Judge Emmet Sullivan of the District of Columbia last year rejected Flynn's claim that he was ambushed by federal agents. Flynn's argument about ineffective assistance is pending. Prosecutors, working with Covington lawyers, are preparing a response to Flynn's allegations.

Covington has transferred hundreds of thousands of documents to Powell. In recent weeks, the firm said it had uncovered additional emails and handwritten notes as it took steps to respond to Flynn's ineffective counsel claims. The firm said Monday that a broader search, beyond Flynn's case file, would take "many weeks to complete."

Covington's latest file search came in response to a late April court order, in which Sullivan gave the firm until Monday to "re-execute" a search of its records and turn over any records that had not previously been transferred.

In the latest search, Covington said it identified 32 additional pages of handwritten notes, which were turned over to Powell on Monday. In April, Covington said a search of its records had revealed the firm had "inadvertently" left certain emails and handwritten notes out of the trove of documents provided to Flynn's new defense lawyer last year.

Powell seized last week on internal FBI records that, she claimed, showed Flynn was set up by federal agents. The newly unsealed emails and notes revealed internal FBI deliberations around investigative and political issues in the buildup to the January 2017 interview at the core of the case against Flynn.

Also in the records were emails in which Lisa Page, then an FBI lawyer, asked whether—and when—Flynn should be warned in his interview that it is illegal to lie to federal agents. The newly released records emerged from an independent review of Flynn's prosecution that was initiated by U.S. Attorney General William Barr.

Responding to the release of the FBI records, President Donald Trump took to Twitter to call the case against Flynn a "scam," igniting fresh speculation that Flynn will soon receive a pardon.

Other observers said conservatives were using the records to manufacture conflict and obscure the fact Flynn cooperated with the special counsel's office and pleaded guilty. Flynn, indeed, had praised the work of his then-defense lawyers at Covington.

"The claimed outrage over FBI tactics is simply a diversion; the relevant issue remains Flynn's repeated lies about his own actions," former federal prosecutor Randall Eliason said in an op-ed.

Read more:

Covington Hands Over More Files to Flynn, After 'Inadvertently' Missing Them Earlier

Why Covington's Constrained as Michael Flynn Flays His Former Defense Team

Who Is Jeff Jensen, Ex-Husch Blackwell Partner and Barr's Point Person on Flynn Case?

'The Record Proves Otherwise': Judge Knocks Down Mike Flynn's 'Ambush' Claims

Flynn's Ex-Covington Lawyers Defend Conduct Amid Court Scrutiny