What is not in doubt, however, is that it was her case, her imprisonment, her hunger-strike protest and her campaign that put the plight of battered women firmly on the agenda, forcing senior judges to acknowledge that the law often did not deal fairly between men and women.
Since domestic violence accounts for one in four of all recorded violent crimes, the fight is not over. But Thornton and others in similar positions have benefited from greater understanding, inside and outside the courts. In two other high-profile cases - Kiranjit Alhuwalia, who burnt to death a husband who had tortured her for 10 years, and Emma Humphreys, who killed her violent boyfriend - murder convictions were reduced to manslaughter by the Court of Appeal.
For the first time appeal judges were taking into account the cumulative effects of sustained violence on the killers. The difference in approach was crucial because it amounted to the judiciary acknowledging battered women's syndrome for the first time, and deciding what effect this would have had on a woman's behaviour.
The shift in attitude is none the less limited, and it remains the case that a man is more likely to be able to run the defence of provocation than a woman.
People who kill can claim self-defence, diminished responsibility or provocation in their defence. For the battered wife, provocation would seem the most obvious, but while the Alhuwalia and Humphreys cases have tilted the law a little more in favour of abused women, it remains a rule that there must be a "sudden and temporary" loss of control. A man is often more inclined to lose control in that way - and to possess the physical strength to give immediate vent to it.
Where there is any delay between the provocation and the response the defence is far trickier. Courts have maintained that any delay is a cooling- off period; lawyers and women's groups seek to widen the definition, insisting that for women it is the complete opposite, a "boiling over" period.
So provocation can lead to the acquittal of a man who suddenly snaps, even if the trigger is something trivial - as in the case of Thomas Corlett, who killed his wife after she moved the mustard pot to the wrong side of the table and was sentenced to three years for manslaughter. Or Joseph McGrail, who at the same time as Thornton killed her alcoholic husband, killed his alcoholic common law wife. He was given a suspended sentence by a judge who said the woman "would have tried the patience of a saint".
There might not have been such a need for the debate on the finer legal definitions of provocation or diminished responsibility if courts could reflect circumstances in sentencing. The Thornton affair has equally illustrated the shortcomings of the mandatory life sentence for murder, which meant she had to receive the same sentence as a hit-man or terrorist who kills dozens.
Senior judges, led by Lord Taylor the outgoing Lord Chief Justice, and numbers of peers, lawyers and academics believe that the inflexibility of the law on homicide is bringing the justice system into disrepute.
Lord Lane, the former Lord Chief Justice not noted for particularly liberal views, said he "cannot believe there is public support" for a law which treats a terrorist who kills with a bomb in the same way as a doctor or relative who helps in a mercy killing or a battered wife who kills her husband. "There is a huge range of murder and to lump them all together and give them the same sentence is wrong," he has said.
But Michael Howard, the Home Secretary, has made clear his view that murder, no matter what the motive, is so serious that it must carry a life penalty. It is an open question whether an incoming Labour government would risk sending a different message to the public.
In the meantime, domestic violence remains a serious social problem. It is true that legal and cultural attitudes have moved on. The police are not so prone to treat cases of wife-battering as "domestics" in which they should not intervene. The 1976 domestic-violence legislation and the increased use of court injunctions have provided some degree of protection. A special five-judge Court of Appeal made history in 1991 by ruling that husbands could be found guilty of raping their wives. That swept away a centuries-old immunity for violent husbands, dating from a 1736 statement by Sir Matthew Hale, the Chief Justice, that "by their mutual matrimonial consent and contract the wife hath given herself in this kind unto her husband which she cannot retract".
But the latest research suggests that one in four women has been the victim of some kind of abuse. Sandra Horley, a social psychologist and chief executive of Refuge, has called for a co-ordinated initiative - with education and training, greater support and counselling, more refuges, and a tough line from the police and courts to deal with the abusers.
Then, conceivably, we would not be dealing with so many domestic killings in the courts.Reuse content