The widow of PC Andrew Harper has said it was “heartbreaking” to be denied “real justice” over his death.
Lissie Harper, 29, said people had been outraged after jurors cleared three men of the police officer’s murder after a trial at the Old Bailey in July.
She has launched a campaign for killers of emergency workers to face mandatory life sentences.
PC Harper’s killers had been accused of murder but were convicted of the lesser charge of manslaughter.
PC Harper, 28, suffered catastrophic injuries when he was dragged behind a getaway car in Berkshire last August.
Mrs Harper said she had received “many messages from people who are outraged” since the verdicts and sentences were handed down.
Her experience of court, which included reading a victim impact statement to a judge, and the “disappointing” result has inspired her campaign.
“One of the hardest things was speaking in court,” she said.
“I had the defendants on my left not really caring what I was saying but I felt it important to speak directly to the judge and tell him what they’d taken from us.
“We had the sense that, although it was going to be an awful and long journey, that at the end of it we might at least get some justice for Andrew.
“Having to endure a trial like that is really hard, so at the end of it to not get any real justice is heartbreaking.”
“The moment I realised it wasn’t an accident was pivotal for me. And the anger built from that moment until the court case.
“It wasn’t until I was looking at them in the eye that I felt the disgrace and just how unfair it is.”
She added: “They knew what they had taken away and the effect that it’s had on so many people.
“They could hear my words so if even on the outside they may not show any sort of remorse I hope that in some way they feel the guilt inside they should feel.”
The killers’ sentences prompted Mrs Harper and PC Harper’s mother Deborah Adlam to launch campaigns calling for killers of emergency service workers to face mandatory life sentences.
Mrs Harper’s campaign, which has been renamed Harper’s Law, calls for all “criminals convicted of killing a police officer, firefighter, nurse, doctor, prison officer or paramedic to be jailed for life. No ifs. No buts”.
She said: “I think that it’s time now to make this change. A lot of people are not pleased with a lot of our laws but this in particular has affected everyone.”
Mrs Harper, whose campaign has been backed by the Police Federation of England and Wales, said the justice system was “broken” and it needed “Harper’s Law to help fix it”.