In an unprecedented move, national Police Federation chairman Paul McKeever also branded the ruling to slash the former Selby bouncer's whole life term as "unforgivable".

Mr McKeever made his accusation in a letter to England and Wales' most senior judge Lord Phillips.

He was immediately supported by the widow of PC Ian Broadhurst, who Bieber shot dead at point blank range in Leeds on Boxing Day 2003.

Mr McKeever said: "Granting an evil, calculated killer any kind of dispensation is criminal, and leaves the judiciary with blood on its hands.

"The decision to surrender to the appeal of this cold-blooded murderer is nothing but unforgivable. I ... urge you to do whatever is needed to reverse this travesty of justice."

Bieber, a former Brayton Junction resident who worked as a doorman at Corinas nightclub in Selby, was told he must die behind bars after being found guilty of murder by a jury at Newcastle Crown Court in 2004.

But the 42-year-old (pictured) must now serve a minimum of 37 years after appeal judges accepted his lawyers' argument the tariff was a "cruel and unusual punishment".

Mr McKeever said: "To say I and the 140,000 police officers I represent throughout England and Wales are appalled and disgusted with the decision is a gross understatement, and my heart goes out to PC Ian Broadhurst's family.

"This is shockingly disrespectful to his memory, and illustrates the utter travesty of our criminal justice system, where the rights of a cop killer outweigh the rights of a fallen officer's family, friends and colleagues. David Bieber is a monster with no consideration for life."

PC Broadhurst's widow Eilisa added: "I'm totally ashamed of those judges, and I'm ashamed to be British. They're not standing up for me or for Ian."