Charles Cooper, of Cooper & Kirk, Photo: Diego M. Radzinschi/ALM

A deputy to former national security adviser John Bolton appears unwilling to withdraw his lawsuit confronting whether President Donald Trump can lawfully block current and former aides from speaking to House impeachment investigators, in spite of their recent decision to rescind a subpoena demanding his testimony.

Charles Kupperman, a former deputy national security adviser, filed a lawsuit against House Democrats and Trump last month seeking clarity on whether he should comply with a congressional subpoena seeking his testimony or follow the White House's instructions to not cooperate. Rather than litigate that question, the House earlier this week withdrew its subpoena, arguing that the move should render the case moot and cause it to be dismissed.

In a letter to the House, Kupperman's lawyer Charles Cooper on Friday said he was "dismayed" that the committees involved in the impeachment probe "have chosen not to join us in seeking resolution from the judicial branch of this momentous constitutional question as expeditiously as possible."

Cooper, who is also representing Bolton, said both of his clients stand ready to testify if the court rules in favor of the House. A hearing in the case is set for Dec. 10 in front of U.S. District Judge Richard Leon of the District of Columbia, a timeline that potentially renders any testimony from Kupperman irrelevant to the fast-moving impeachment inquiry.

"It is important both to Dr. Kupperman and to Ambassador Bolton to get a definitive judgment from the judicial branch determining their Constitutional duty in the face of conflicting demands of the legislative and executive branches," Cooper said in Friday's letter.

House leaders earlier this week suggested that the key question raised in Kupperman's suit would be resolved more quickly in a separate case confronting the would-be testimony of former White House counsel Donald McGahn. But Cooper disputed that any decision in the McGahn case, pending before a different trial judge in Washington, would have a bearing on Kupperman and Bolton.

In their push for McGahn's testimony, House lawyers have underscored that they are not seeking information from him concerning national security and foreign affairs. House lawyers have acknowledged that, if lawmakers were pursuing that information, the president's assertion of so-called "absolute testimonial immunity" over his former White House counsel might have been valid.

"Here, unlike McGahn, information concerning national security and foreign affairs is at the heart of the the committees' impeachment inquiry, and it is difficult to imagine any question that the committees' might put to Dr. Kupperman that would not implicate these sensitive areas," Cooper wrote in Friday's letter to House general counsel Douglas Letter.

The McGahn case is much further along than the Kupperman matter. U.S. District Judge Ketanji Brown Jackson of the District of Columbia recently heard arguments, and she appeared to lean toward a ruling in support of the House's effort to secure McGahn's testimony. The judge is expected to rule by the end of this month.

Cooper contested the House's suggestion that Kupperman filed his lawsuit as a delay tactic. House leaders, he said, "are mistaken to say Dr. Kupperman's lawsuit is intended 'to delay or otherwise obstruct the committees' vital investigatory work.'"

"Nor has the lawsuit been coordinated in any way with the White House, any more than it has been coordinated with the House of Representatives," Cooper wrote. "If the House chooses not to pursue through subpoena the testimony of Dr. Kupperman and Ambassador Bolton, let the record be clear: that is the House's decision."

US District Judge Richard Leon in Washington. Photo: Diego M. Radzinschi/NLJ

During a telephone conference Wednesday, Leon declined to back away from the schedule he'd earlier set for the case, telling the lawyers that the expedited briefing schedule "will remain intact." The first round of court papers are due next week.

"I fully appreciate that the decision to voluntarily dismiss this lawsuit is solely up to Mr. Kupperman and his counsel," Leon said. "I will say nothing further on that point."

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