A husband who allegedly subjected his wife to years of abuse was not criminally responsible for her suicide, appeal court judges have ruled.
The judgement could pave the way for similar cases
But the court signalled similar cases could result in a trial, even when the partner did take their own life.
The three judges upheld an Old Bailey judge's decision to throw out the case against Harcharan Dhaliwal.
His wife Gurjit hanged herself in London in 2005. He was charged with manslaughter but acquitted in March.
Mrs Dhaliwal's death was seen as a test case for domestic violence by women's groups. She was found dead in an outhouse at her home in Southall, west London on 22 February 2005.
In March an Old Bailey judge threw out charges of manslaughter and grievous bodily harm, and reporting restrictions were lifted on Tuesday.
Judge Jeremy Roberts QC said there was no basis on which a properly directed reasonable jury could convict him.
But he also called for a review of the law to perhaps make it possible for manslaughter prosecutions to be pursued in the future.
At the appeal court on Tuesday, Sir Igor Judge, Mr Justice Henriques and Mr Justice Fulford upheld his decision.
Responding to their decision, Mrs Dhaliwal's brother, Nav Jagpal, said however his sister clearly experienced years of mental abuse and violence.
"I am sickened to learn that English law is unable to prosecute a man for perpetrating psychological manslaughter - how can there be so much evidence and yet no punishment?" he said.
The case had proceeded on the basis no reasonable jury could be satisfied Mrs Dhaliwal suffered from a "recognised psychiatric illness".
Sir Igor said the problem for the court to address was whether psychological injury, not recognisable psychiatric illness, fell within bodily harm.
Setting out the background to the case, Sir Igor said evidence emerged after her death that she was physically and psychologically abused by her husband during a period of years.
On the night she died, they argued and he admitted later that he struck her on the forehead.
The judge said: "The bangle he was wearing at the time cut her skin at the point where his blow landed. It seems likely that this assault operated as the immediate trigger which precipitated her suicide.
He added: "Psychiatric evidence suggested that the 'overwhelming primary cause' for the suicide 'was the experience of being physically abused by her husband in the context of experiencing many such episodes over a very prolonged period of time'".
The CPS said it was "disappointed" at the court's decision. Nazir Afzal said: "The decision to bring a prosecution was not taken lightly.
"We desperately wanted the jury to hear about the life of Gurjit and what she is alleged to have suffered at the hands of her husband, Harcharran.
"Regrettably that won't happen now.
The Old Bailey heard police were called to the Dhaliwals' home five times, between 1998 and 2003, and Mrs Dhaliwal received medical treatment on three occasions.
The police consulted Dr Roxane Agnew-Davies, a clinical psychologist who specialises in the effects on women of domestic violence. She analysed a diary Mrs Dhaliwal kept of the last five months of her life.
She concluded Mrs Dhaliwal "did sustain psychological injury, characterised by features of depression and post-traumatic stress disorder, as a result of the domestic violence she experienced within her marriage".
She listed seven types of "psychological phenomena" that contributed to her suicide including loss of hope and feeling trapped by practicalities.
But the judge pointed out two of the prosecution's three experts believed Mrs Dhaliwal was not suffering from a psychological illness at the time of her death.
He felt it was not possible, under current law, to hold Mr Dhaliwal criminally responsible for a "psychological injury".
Judge Roberts suggested the Law Commission in its homicide review could examine whether the law could provide a "less convoluted route" to manslaughter in such cases.
Sandra Horley, chief executive of Refuge, the national domestic violence charity, called for it to review the area of psychological manslaughter.
"Suicides following assaults and bullying are sadly an all too common occurrence and the law should recognise this phenomenon," she said.
She added "the charity was "deeply disappointed" by the ruling. "It flies in the face of natural justice," she said.