Shouts of "The law acquits, the police murders!" and "No justice, no peace!" greeted the court's decision and security officers cleared the court in Bobigny, a town outside Paris in Seine-Saint-Denis, a department with a high crime rate.
But the large number of off-duty police officers who had turned out to support their colleague, Damien Saboundjian, were pleased with the result and his lawyer, Daniel Merchat, declared himself "very happy" with the judgement.
The public prosecutor had asked for a suspended five-year sentence and a ban on Saboundjian practising his profession, accusing him of manslaughter, a crime that can mean prison sentences of up to 20 years in prison.
Saboundjian shot Amine Bentounsi in the back after being summoned by a tip-off that a known armed robber had been spotted outside a bar in Noisy-le-Sec in Seine-Saint-Denis in April 2012.
He claimed that he was acting in self-defence because Bentounsi had drawn a gun on him.
The Bentounsi family's lawyer, Michel Konitz, pointed to apparent inconsistencies in the accounts of Saboundjian and his colleagues, who, when challenged with the fact that the victim had been shot in the back, claimed he had turned when Saboundjian fired, although they had made no mention of him doing so in their initial statements.
Other witnesses said that Saboundjian fired wildly, at one point aiming at a car and hitting another one.
"They can carry on shooting us," commented Bentounsi's sister Amal, who set up a campaign against alleged police violence after her brother's death. "Police impunity continues. France is not prepared to find the police guilty even when they have killed. Justice has shot itself in the foot."
Police trade unions and the right-wing Republicans party have recently been pushing hard for police to be allowed to use their weapons after warning they might do so.
Republicans MP Eric Ciotti welcomed Friday's verdict, claiming that it "once again" showed that current legislation is out of date.
In 2014 7,603 police officers and gendarmes were injured in the course of their duty, according to an official report leaked to Le Figaro newspaper, a five per cent rise on the previous year.