Washington CNN  — 

A federal judge on Monday dismissed a lawsuit that former Trump national security official Charles Kupperman had filed challenging a House subpoena for him to testify in the impeachment inquiry after the chamber withdrew their subpoena.

Judge Richard Leon wrote in a 14-page opinion that there is no expectation that the House will reissue the subpoena, therefore the lawsuit is unnecessary.

Notably, by ruling the case is moot, Leon was able to sidestep the thorny issue of separation of powers and whether the White House could claim some administration witnesses have immunity.

Leon, however, noted that things can change in the future.

“Have no doubt though, should the winds of political fortune shift and the House were to reissue a subpoena to Dr. Kupperman, he will face the same conflicting directives that precipitated this suit. If so, he will undoubtedly be right back before this Court seeking a solution to a Constitutional dilemma that has long-standing political consequences: balancing Congress’s well-established power to investigate with a President’s need to have a small group of national security advisors who have some form of immunity from compelled Congressional testimony.”

He added: “Fortunately, however, I need not strike that balance today!”

The House had withdrawn their subpoena for Kupperman’s testimony in November, writing in a court case, “The subpoena at issue in this matter has been withdrawn and there is no current intention to reissue it.”

Despite his relatively short tenure, Kupperman had initially drawn the interest of House investigators who believed he had first-hand knowledge of Trump’s decisions regarding Ukraine that have come under scrutiny in the impeachment investigation.

Specifically, Kupperman was listening in on the July 25 phone call when, according to a White House transcript, Trump pressed Ukrainian President Volodymyr Zelensky to investigate former Vice President Joe Biden.

Yet the White House sent a letter to Kupperman directing him not to comply with the subpoena he received from the House committees and maintaining that he would be protected by “constitutional immunity.”

A longtime associate of former national security adviser John Bolton, Kupperman served in several positions in the Reagan administration and subsequently served as a space operations executive at Lockheed Martin and in Boeing’s missile defense sector.

This story has been updated with additional background on the case.

CNN’s Zachary Cohen contributed to this report.