By Katelyn Polantz, CNN

(CNN) -- A federal appeals court on Tuesday is considering whether former national security adviser Michael Flynn should have his case dismissed immediately because he shouldn't have been interviewed by the FBI in the early days of the Trump administration and thus should never have pleaded guilty to lying, according to the Justice Department's reasoning.

The case has had countless twists since Flynn, a retired Army lieutenant general and top intelligence official, pleaded guilty almost three years ago to lying to the FBI about his talks with the then-Russian ambassador about approaches that would undermine Obama administration policy before Trump took office.

The DC Circuit Court of Appeals hearing Tuesday morning may be the most consequential yet in the years of court hearings for Flynn.

Ten judges on the appeals court are rehearing the arguments, after wiping out a previous Circuit Court ruling that ordered a quick dismissal earlier this summer.

The case is ultimately a separation of powers fight between a judge's authority and the Justice Department's decision to drop a prosecution, set against the political divide over the Russia investigation, which President Donald Trump, Attorney General William Barr and Flynn's lawyers have fueled this year by questioning how the FBI conducted the probe.

The arguments Tuesday may touch on some intense debates related to Flynn, including whether the Justice Department's dismissal of the case was out of line with typical law enforcement decisions and whether his trial-level judge, Emmet Sullivan of the DC District Court, handled the case fairly.

Before Flynn prompted appeals, Sullivan had questioned the Justice Department's about-face in the case by asking a former federal judge to argue against the dismissal. Sullivan also had planned to hold a hearing before deciding what to do, which he suspended as the appeals courts considered the standoff. Sullivan appeared to be weighing whether he could sentence Flynn without prosecutors' support and whether Flynn could be held in contempt for potentially perjuring himself by swearing separately under oath that he was both guilty and innocent.

Flynn was set to serve a likely zero to six months in prison for lying.

He called Sullivan's moves to check the Justice Department errors in court, and the Trump Justice Department argued that it alone can decide when a defendant is prosecuted.

Sullivan "fails to justify the district court's unprecedented intrusions on individual liberty and the Executive's charging authority," DC Appeals Court Judge Neomi Rao, a Trump appointee, wrote in the circuit's prior 2-1 opinion in the case.

A ruling in favor of Flynn could lead to his case's dismissal and strip Sullivan of the power to question the Justice Department's prosecution decision, while a ruling in favor of the judge could keep Flynn's criminal case alive in court --potentially for several more weeks or even into 2021. No ruling is expected Tuesday.

Though full court hearings are extremely rare at the DC Circuit, this is the second time the court has reheard a case related to the Mueller investigation -- the first being the House subpoena of former White House counsel Don McGahn, which the court decided last week by affirming Congress' right to sue and sending proceedings back to the trial-level judge.

DC Circuit Judge Greg Katsas -- a Trump appointee who worked in the White House counsel's office while Flynn was national security adviser -- has apparently recused himself from the arguments and will not hear the case on Tuesday. That leaves the makeup of seven Democratic appointees and three Republican appointees on the court as a potential uphill climb for Flynn.

The Flynn case has prompted criticism from Republicans on the worthiness of the Russia investigation, from Democrats and former prosecutors on Barr's decision to drop Flynn's charge and from Flynn supporters on the approach taken by Sullivan.

In recent weeks, Barr has relied on one of his US attorneys to send FBI documents from the early Russia investigation to the Flynn legal team, which they then make public in court filings.