Two U.S. Park Police officers fired 10 shots in a span of 25 seconds when they killed unarmed motorist Bijan Ghaisar in 2017. But whether they can be prosecuted in state court, as Fairfax County is now seeking to do, will likely involve convincing a federal judge that the shooting was not “necessary and proper,” a standard few state prosecutors have ever met.

On Thursday, Officers Lucas Vinyard and Alejandro Amaya were indicted by a Fairfax County grand jury on one count each of involuntary manslaughter and reckless discharge of a firearm. In November 2017, they shot and killed Ghaisar, 25, as he slowly drove away from them during a traffic stop in the Fort Hunt area of Fairfax. Last year, federal authorities declined to file federal civil rights charges, so Fairfax Commonwealth’s Attorney Steve Descano picked up the case and obtained state criminal charges.

But federal officers are largely exempt from state jurisdiction under the Supremacy Clause of the Constitution, which says that states must defer to federal law. Descano said Thursday that he anticipated the officers’ lawyers would remove the case to federal court, and then invoke the Supremacy Clause in a motion to have the case dismissed. He requested help from Virginia Attorney General Mark Herring to argue against the motion, and Herring’s office agreed to take the case on. No matter which side prevails in the officers’ case, an appeal is likely.

States have tried to prosecute federal officers before, with little luck. But there has been at least one judicial finding that federal officers aren’t completely shielded from state prosecution, in the high profile “Ruby Ridge” shooting by an FBI agent. And an appeal in the Ghaisar case would go to the U.S. Court of Appeals for the 4th Circuit, which in June allowed a lawsuit to proceed against officers with the conclusion about police shootings, “This has to stop.”

Vinyard, 39, and Amaya, 41, who have said they believed Ghaisar’s driving was a danger to them or others, had not yet surrendered on warrants as of Friday afternoon. “We are not giving them any preferential treatment,” said Antonio Peronace, a spokesman for the Fairfax prosecutor. 'We have entered the warrants, they are active, and we fully expect that they will be in custody soon."

It was not immediately clear Friday who was representing the officers. The lawyers who represented Vinyard during the two-year FBI investigation of the shooting, David Schertler and Danny Onorato, said Friday they were no longer Vinyard’s counsel, and Kobie Flowers, who represented Amaya, declined to comment. The U.S. attorney’s office in Alexandria declined to comment on whether they might defend the officers. The officers have been working on paid administrative duty since April 2018, but the Park Police refused Friday to say whether Vinyard and Amaya were still on the job.

It’s also not clear what effect the indictments will have on the civil suit the Ghaisar family has pending against the Park Police, which is scheduled for trial next month. The government previously requested a stay of the trial, pending resolution of any criminal case in Fairfax, but Senior U.S. District Judge Claude M. Hilton denied that request. Now charges have been filed. Federal attorneys have not made another request for a postponement, and Hilton is considering motions for summary judgment in the case from both sides, with a hearing scheduled for Friday.

The legal criteria for overcoming the Supremacy Clause have been made clear in a series of cases dating to the 19th century, when the logic held that unruly state authorities were trying to overstep their bounds. “Providing a federal forum protects federal officers,” former Solicitor General Seth Waxman and Cornell law professor Trevor W. Morrison wrote in 2003, “from state courts’ potential hostility to federal policies and institutions.”

Once in federal court, the federal officers must show that they were authorized to act under federal law, and did “no more than what was necessary and proper for him to do,” according to a ruling first issued in 1890. For conduct to be “necessary and proper,” the officer must believe that their actions were “objectively reasonable.”

These criteria were put to the test most recently in Texas, when an Austin police officer, deputized as an FBI task force agent, shot and killed an unarmed man during a scuffle in 2013. The officer, Charles Kleinert, said that he had been chasing the man while holding a gun, caught him, and when he struck the man in the back while they were wrestling, the gun went off and killed Larry Jackson Jr.

The Travis County district attorney obtained a manslaughter indictment for Kleinert in 2014. Kleinert’s lawyers removed the case to federal court, where a judge ruled that Kleinert’s “actions were no more than what was necessary and proper to detain and arrest Jackson,” and dismissed the case. The Travis County prosecutor, Rosemary Lehmberg, appealed to the 5th Circuit and lost again, with the court ruling that Kleinert “satisfied each element of the Supremacy Clause immunity analysis.”

“The fact is that [Kleinert] was working in a federal capacity and carrying out his federal duties,” his lawyer Randy Leavitt told The Post in 2015. “So as long as he was acting in good faith, which he was, he is immune from state prosecution.”

Travis County hired former Texas Supreme Court chief justice Wallace B. Jefferson to appeal the Kleinert case to the U.S. Supreme Court. He said they “argued that the subjective standard was itself wrong because it was premised on outdated case law, and that the better rule would be one that focuses more on the objective reasonableness of the officer’s actions.” The Supreme Court declined to hear the case.

Ghaisar’s case has some key differences. For one, the shooting and the minutes of pursuit leading up to it were captured on video, unlike the Kleinert case. And Ghaisar was not being pursued for a felony — he had left the scene of a fender bender in Alexandria. Twice he stopped while being pursued by Vinyard and Amaya down the George Washington Memorial Parkway, and twice he drove off when the officers ran at his Jeep Grand Cherokee with guns drawn.

When Ghaisar stopped a third time, and started to drive off again, both officers fired five shots into the Jeep, striking Ghaisar four times in the head. The officers told the FBI last year that they believed Ghaisar was driving toward Amaya, though they appear to be on the side of the Jeep when they start firing in the video, and that his erratic driving made him a danger to the community.

Nicholas Bacarisse, who joined Jefferson in appealing the Kleinert case to the Supreme Court, said of the Ghaisar case, “I don’t think the court can just look at the video and ask whether the conduct was ‘necessary and proper.’ ” He said a federal judge will probably make a determination under the “modern qualified immunity analysis, or did clearly established law prohibit the officers’ actions. And under that test, which is itself deeply flawed, officers get off for this sort of conduct all the time, no matter how outrageous it seems to us citizens.”

But one federal court found that there were circumstances where a federal officer could be prosecuted with state charges. In 1992, FBI sniper Lon Horiuchi was part of a team attempting to arrest Randy Weaver in Ruby Ridge, Idaho, on gun charges. But Horiuchi shot and killed Weaver’s wife. After the Justice Department declined charges, the local Idaho prosecutor charged Horiuchi with involuntary manslaughter.

The case was removed to federal court, which granted Horiuchi’s Supremacy Clause immunity request. But the U.S. Court of Appeal for the 9th Circuit Court reversed that ruling, saying “That immunity has limits. When an agent acts in an objectively unreasonable manner, those limits are exceeded, and a state may bring a criminal prosecution.” In that case, a group of former U.S. attorneys general, led by now U.S. Attorney William P. Barr, filed an amicus brief supporting the Supremacy Clause argument.

After winning the appeals court ruling, Idaho prosecutors dropped the charges.

Thomas Connolly, a former federal prosecutor and now one of the Ghaisars’ lawyers, said that “the family understands that Bill Barr’s Department of Justice is going to put any impediment it possibly can to the prosecution of these officers.” The Justice Department has refused to allow the FBI agents who initially investigated the case to cooperate with Fairfax’s investigation, and it is defending the Park Police in the Ghaisars’ civil suit.

Charlotte Gomer, a spokeswoman for Virginia Attorney General Mark Herring, said they had joined the case because “this case is of tremendous importance to the Ghaisar family, the Northern Virginia community, and the Commonwealth as a whole, and Attorney General Herring believes it is important to stand up for the principles of accountability and justice.” She noted that Herring’s attorneys wrote the lead amicus brief in the Supreme Court case involving Trump’s taxes, “and this case will likely involve similar issues.”

Once Vinyard and Amaya are arraigned in Fairfax, they have 30 days to file a motion to remove the case to federal court. Connolly said once a motion is filed to dismiss the case, both sides will likely be given time to file briefs and replies, followed by oral argument, and then a ruling from the judge. He and others expected that whoever loses that ruling will appeal to the 4th Circuit, and some lawyers think that a ruling there may not end the issue — it could then be appealed to the Supreme Court, as Kleinert’s case was. That would push a possible criminal trial at least to late next year and possibly into 2022.