At least one in five domestic violence perpetrators who would have previously been charged are now "getting away with it" Labour has claimed.
Yvette Cooper, the shadow home secretary, has accused Theresa May of failing victims as figures revealed a 13% decrease in the number of cases being referred to the CPS for consideration in the last three years.
Cooper also blamed cuts to frontline policing for the decline.
The figures, retrieved through a Freedom of Information request by Labour, come after a 23% rise in referrals between 2007 and 2010 and amid a nearly 10% increase in the number of domestic violence reports to police.
Ms Cooper said: "These are shocking and disturbing figures.
"Theresa May claimed in 2010 she was pursuing a 'unique opportunity to bring about real change' on domestic violence. Instead these figures show things have gone backwards and she is failing badly.
"Domestic violence cases reported to the police have increased by nearly 10%. Yet at the same time the vast majority of police forces have cut the number of cases they refer for prosecution by 20%.
"And this big drop in referrals has all happened since cuts to frontline policing started. Referrals and prosecutions were going up before the election. But now, fewer police officers are referring fewer domestic violence cases for prosecution and victims are being let down as a result.
"That means one in five perpetrators who would previously have been charged are now getting away with it."
She called for a "step change" in dealing with domestic abuse including better police training and support for victims.
A Home Office spokesman said: "This Government has driven forward significant progress in tackling violence against women and girls. We have ring-fenced nearly £40 million for specialist local domestic and sexual violence support services, strengthened the protection in place for victims through the pilot of Clare's Law and our national advertising campaign is helping youngsters spot the early signs of abuse.
"Domestic violence, rape and sexual offence prosecutions have reached their highest ever conviction rate for the second year running - so the systems in place to protect women are working, despite the necessary cuts to police budgets.
"But there is still much to do. We are actively pursuing ways in which we can prevent domestic and sexual violence happening in the first place, encourage more victims to come forward and improve the police response. We won't stop until we have eradicated these appalling crimes for good."
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