Story highlights Trump's lawyer has made accusations against fired FBI director Comey

A prosecution of Comey would be a complete disaster for the president, Callan says

Paul Callan is a CNN legal analyst, a former New York homicide prosecutor and currently is of counsel at the New York law firm of Edelman & Edelman PC, focusing on wrongful conviction and civil rights cases. Follow him on Twitter @paulcallan. The opinions expressed in this commentary are his own.

(CNN) The President and his personal attorney, Marc Kasowitz, should be careful what they wish for.

In his aggressive defense of President Trump, Kasowitz has in substance accused the former Director of the FBI of leaking "privileged communications" and of possibly committing perjury in his testimony before the Senate Intelligence Committee on Thursday.

The Kasowitz accusations, made shortly after James Comey completed the public portion of his Senate testimony, if actively pursued, would necessarily shroud the Trump administration in a complex web of investigations, congressional hearings and court proceedings that would ultimately pull it into a black hole of legal destruction.

If Kasowitz' s accusations of criminal conduct against Comey were accepted and believed by the Senate and federal prosecutors and a federal grand jury indictment followed, the result would be a criminal trial of the former FBI director, requiring the testimony under oath of the President of the United States. Trump said Friday that he'd be willing to testify under oath "one hundred percent."

Such a grand jury investigation and presentation would necessarily require the appointment of a second "special counsel" or the creation of a new independent prosecutor to avoid any interaction and conflict with the Justice Department, which nominally directs and controls the current Robert Mueller-led investigation under existing law. Mueller's current appointment authority doesn't cover investigation of the FBI or its former director.

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