Domestic abuse to include non-violent control
The definition of domestic abuse has been widened to cover psychological intimidation and controlling behaviour and apply to victims under the age 18.
It means acts such as preventing partners from leaving the house or having access to a phone could lead to a prosecution.
It is hoped the broadened definition will increase awareness of what domestic abuse is and who suffers it.
The Home Office says more prosecutions could be brought as a result.
It also wants more youngsters to come forward and access the support they need - for example, speaking to someone about the abuse or contacting a helpline or a specialist service.
The changes, which will be implemented in March 2013, follow calls from local authorities, police and voluntary organisations.
There is no specific criminal offence of domestic violence. Instead, a definition that refers to "incidents of threatening behaviour, violence or abuse" was adopted in 2004.
Ministers say that has led police and prosecutors to make too narrow an interpretation of the term and let some perpetrators off the hook.
One victim, who asked to remain anonymous, said had the new guidelines been in force while she was suffering, she might have sought help earlier.
"There were several incidents of violence over the six years that I suffered. However, there were many more incidents of psychological and emotional abuse that went on even if there was no violence.
"These were about control and power and diminishing my self-esteem to the point of not being able to see what was going on or trust my own instincts.
"Because there were fewer incidents of violence, I didn't consider myself a victim of domestic violence.
"Only after when the violence escalated, when divorce proceedings were started and my ex-husband started losing control over me, and the children witnessed the abuse, did I realise I was a victim and I must do something.
"If I had been more aware that I was suffering the psychological abuse and emotional abuse, I may have been more able to see what was going on and get the help I needed for me and the children much sooner."
The Association of Chief Police Officers said that an average of two women a week and one man every 17 days were murdered by a current or former partner.
Chief Constable Carmel Napier, of Gwent police, said: "The amendments to the definition are key in helping to raise awareness and enable effective prevention working in partnership with all agencies.
"Domestic abuse ruins lives. In some cases it ends in homicide. This amended definition will help us all to work together to defeat this dreadful crime."
Some lawyers and campaigners questioned how effective the changes would be in bringing more cases to court.
Rachel Horman, head of domestic violence and forced marriage issues with the law firm Watson Ramsbottom, said she welcomed any attempt to increase the arrest rate for domestic violence, but added: "I am a little bit sceptical about how much of a difference this is going to make".
"It would certainly help if a new offence of coercive control was created because I think that gives the police much more to work with. As it stands the government are expecting the police to prosecute under the protection from harassment act, which is already notoriously underused by the police."
Ms Horman urged the government to invest in training for the police, prosecutors and judges "in the devastating effects of psychological abuse... without that I really don't think that these cases are going to come to court".
Deborah McIlveen, of Women's Aid, said: "We particularly welcome that the definition of domestic violence now encompasses the high levels of young people aged 16 to 18 who are experiencing abuse in their intimate partner relationships and that the definition recognises the enormous impact of coercive control.
"The challenge now is to ensure that police officers are able to identify coercive control and take appropriate action for both adult survivors and 16 to 18-year-olds.
"Domestic violence has always been grossly under-reported so if this is implemented properly it could help build public confidence in the police and result in more victims reporting the domestic violence and more perpetrators can be held to account and stopped from using domestic violence."