Lauren Smith says she was denied justice as her attacker was cautioned
Almost 40,000 cases of assault were dealt with by cautions in England and Wales last year, the BBC has learned.
Justice Secretary Jack Straw announced a review on Monday into the use of cautions.
Research by Panorama found 739 people charged with grievous bodily harm were given cautions.
The findings have led to claims that out-of-court punishments are being used for more serious crimes than intended.
Mr Straw told the BBC he was worried about the regional disparity in the use of cautions and said: "I understand the concerns that have been raised."
He added that there were very clear guidelines about when cautions should be used and said it was "absolutely not the case" they were being handed out as means of keeping prison numbers down.
Meanwhile, the director of prosecutions has said a more coherent approach is needed.
CAUTIONS: THE FIGURES
Results from 39 of 41 police forces in England and Wales surveyed
38,952 cautions issued for actual bodily harm (ABH)
739 cautions issued for grievous bodily harm (GBH)
Half of all criminal cases dealt with using cautions
Cautions are not used in Scotland
In England and Wales, half of all criminal cases are now punished out of court by way of cautions, warnings and fines - direct measures meant to be fast and fair and aimed at cutting costs and unclogging the courts system of minor offences like anti-social behaviour.
Cautions are formal warnings, issued at the discretion of the police if the offender admits their guilt.
But there is widespread concern about a system that lacks scrutiny.
The research by the BBC found cases of burglary, child neglect, sexual assault and even rape that were dealt with by caution in 2008.
The head of the Metropolitan Police, Sir Paul Stephenson, said there had been an "almost uncontrollable increase" in cautions.
He told the Sunday Times: "We've ended up cautioning far too many people.
"If a huge thug comes and hits someone in the face for no reason and that person then gets off with a caution the following day because he's expressed remorse when he's sobered up, it's fundamentally not right."
He said that efforts to ease pressure on the justice system had led to officers being expected to hand out punishments, distracting them from their traditional policing role of preventing and detecting crime.
Among those who feel short-changed by the system is Lauren Smith, a 26-year-old flight attendant from Newcastle, who was bitten and beaten up by a man who used to be a friend. She has been left permanently scarred. Her attacker received a caution.
She said: "He's walking around scot-free thinking he's got away with it. People will think, 'Oh, well, if I punch a girl in the face that's OK, I'm just going to get a caution.' It means nothing."
The Association of Chief Police Officers (Acpo) said the figures were not proof that its forces had gone soft on assault. It pointed out that actual bodily harm (ABH) was any assault that resulted in injury, and not all of those injuries would have been serious.
But the Crown Prosecution Service (CPS) has recently issued clear guidelines about how assault should be treated.
A different type of out-of-court punishment - called a conditional caution and issued by the CPS rather than the police - was introduced in England and Wales in 2006.
In these cases, the offender must agree to apologise to the victim, pay compensation or take part in a treatment programme to tackle their offending behaviour.
But the CPS now says that anything above the most minor assault - common assault - is too serious to be punished by conditional caution.
The Director of Public Prosecutions, Keir Starmer, told Panorama the gradual introduction of different out-of-court punishments - some of which were administered by the police and others by the CPS - had led to a lack of consistency.
"I accept that what is needed is a coherent system across the board with one overarching scheme."
Panorama: Assault on Justice, BBC One, Monday, 9 November, at 2030 GMT.