An inquiry is now investigating the circumstances surrounding Mr Baker’s death, including the way a police operation to intercept the prison break was planned.
In an opening statement, on Wednesday morning, Phillippa Kaufmann QC said Mr Baker’s mother Margaret Smith and his family are “incensed” at the way the case has been handled by Scotland Yard.
“The family have been searching for answers to these questions for five and a half years. They have faced many obstacles”, she said.
“Margaret says Jermaine should have been arrested and prosecuted along with the others involved. She is categorically and unequivocally clear that whatever Jermaine was doing on December 11, 2015, he shouldn’t have paid with his life, that his death was entirely unnecessary and unjustifiable.
“It was the result of truly reprehensible failures on the part of police officers involved.”
The firearms officer - referred to as W80 - who fired the fatal shot at Jermaine Baker is locked in a protracted legal battle over possible disciplinary proceedings, and has not faced a criminal prosecution.
The officer in charge of the operation, Detective Chief Inspector Neil Williams, was allowed to retire before he could face any disciplinary proceedings.
Ms Kaufmann said the family of Mr Baker were “incensed by the Commissioner of the Metropolitan Police’s decision to permit Detective Chief Inspector Neil Williams - an absolutely central character in this inquiry - to retire at a time when he was being investigated by the IPCC for serious failure in his management of the operation.
“And incensed that W80 is currently discharging a firearms training role where he is called upon as a mentor and educator of future generations of MPS firearms officers.
“The Commissioner has demonstrated to the family she is not at all interested in holding her officers to account, either to the code of ethics or to the Rule of Law.
“She is unwilling or incapable of challenging the culture of institutional defensiveness and impunity that has pervaded firearms policing for decades.”
Ms Kaufmann added that Mrs Smith “is deeply saddened to see in the evidence an attitude by the officers to Jermaine that tragically mirrored treatment he had suffered in his life.
“This was not an operation that had regard to the value of Jermaine’s life. On the contrary, it was because these officers diminished and devalued Jermaine that his life was ultimately brought to an end, including by the premature judgement of W80.”
She urged the inquiry to look into why Mr Baker, who was unarmed in the car, was shot by W80, and what steps the Met took to safely arrest him when they launched the operation.
W80 says he believed Mr Baker was reaching for a gun when he opened fire. No firearm was found in the stolen Audi, but police recovered an imitation Uzi machine gun from the back of the vehicle.
Police knew about the prison break plot in advance, and decided to allow it to continue in a bid to catch everyone involved and also seize firearms they believed would be involved.
Senior judges and a prison governor agreed to the interception plan, but questions will be asked in the inquiry about whether they were involved in the decision-making process or simply presented with a “settled” plan.
The inquiry continues.