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 murdering her husband following 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 driven by Henry Long in Berkshire last August.
Mrs Harper told the BBC she had received "many messages from people who are outraged" since the verdicts and sentences were handed down.
She said her experience at the Old Bailey, which included reading a victim impact statement, and the "disappointing" trial result, had inspired her campaign.
Speaking in the witness box was "one of the hardest things", she added.
"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," she said.
"We had the sense that, although it was going to be an awful and long journey, at the end of it we might at least get some justice for Andrew.
"So at the end of it, to not get any real justice is heartbreaking."
The trial heard how PC Harper had responded to reports of a quad bike theft with a colleague hours after their shift had ended.
As he attempted to apprehend one suspect, his feet became entangled in a rope trailing behind a getaway car which led to him being dragged to his death.
Mrs Harper said it "wasn't until I was looking at them [the defendants] in the eye, that I felt the disgrace and just how unfair it is".
"They knew what they had taken away and the effect that it's had on so many people," she said.
"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 sentences of PC Harper's killers prompted Mrs Harper and PC Harper's mother Deborah Adlam to launch campaigns calling for tougher sentences for killers of emergency service workers.
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 the campaign, backed by the Police Federation of England and Wales, would "help fix" a "broken" justice system.
Mrs Harper, who like her husband is from Wallingford in Oxfordshire, said Harper's Law was "about the protection [emergency workers] need and potentially a deterrent for criminals".
She hopes to meet Prime Minister Boris Johnson and Home Secretary Priti Patel to discuss her campaign after they both sent letters to her offering their support during the court case.
Mr Justice Edis, the sentencing judge, said each of the jail terms for PC Harper's killers had to reflect "the seriousness of this case".
The maximum sentence a judge can impose for manslaughter is life imprisonment but they must specify a minimum term to be served.
The Attorney General's Office said it had been asked to review the sentences and has until 28 August to decide if the Court of Appeal should review them.
Mrs Harper said her husband "just wanted to protect people. He knew what was right and what was wrong and would have worked all the hours if he could".
"Andrew made the ultimate sacrifice and it wasn't just his life - it was his future and my future and the lives of everyone who loved him," she added.
"I constantly felt that he had my back and that's why Harper's Law is so important for me. I want to do it for him."