Two of PC Andrew Harper’s killers have launched appeals against their manslaughter convictions.
The police officer sustained catastrophic injuries when he was dragged behind a getaway car driven by Henry Long in Berkshire last August.
Albert Bowers and Jessie Cole, who were also in the car, have lodged applications with the Court of Appeal.
PC Harper’s mother Debbie Adlam called the pair’s appeals a “kick in the stomach”.
Following a trial at the Old Bailey, Long, 19, was jailed for 16 years while passengers Bowers and Cole, both 18, were sentenced to 13 years each.
Bowers and Cole are seeking permission to challenge their convictions and sentences.
Ms Adlam said: “We’ve only just come through the first anniversary of Andrew’s death.
“It’s been the most painful year of my life and the trial was absolutely gruelling.
“We clearly didn’t get the justice that we all felt that we deserved – but this application to appeal both conviction and sentence is a further kick in the stomach.
“We will obviously have to leave it up to the judicial system but I’d like to think that I do not live in a country where people can be involved in taking a life whilst committing a crime and be allowed to walk away from it and serve anything other than a lengthy custodial sentence.”
Earlier this month, the Attorney General’s Office confirmed it had been asked to review the killers’ sentences after claims they are too lenient.
PC Harper, 28, from Wallingford, Oxfordshire, had only been married for a month when he died on 15 August last year.
On Tuesday his widow Lissie said it was “heartbreaking” to be denied “real justice” over his death.
She has launched a campaign for killers of emergency workers to face mandatory life sentences.
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”.
Mrs Harper has declined to comment on the appeals launched by Bowers and Cole.
No date has been set for the appeals to be heard.