Matt Cane, General Secretary of the Metropolitan Police Federation, said: "This is frankly a nonsensical ruling by the IOPC that will shock police officers across London and indeed the country.
"Police officers should not have their livelihoods or liberty put at risk for performing what unequivocally, as has been found in a court of law, is their lawful and appropriate function.
"And yet putting this brave officer on trial for murder - as astonishing as that was - was not enough for the IOPC. Being cleared unanimously by a jury who heard all the evidence was not enough for the IOPC. They have now decided to put him and his family through more torment.
"This is not accountability. This is not in the public interest. This is not right or fair or just.
"We will be vigorously defending the actions of Sgt Blake at any conduct proceedings.
"And as a Federation, we continue to work with the Metropolitan Police Service to ensure that colleagues, who make the decision to carry firearms, remain fully supported in their difficult and demanding jobs."
