The new vetting regime for people who work with children will come in as a result of an outcry over several cases where sex offenders were cleared to work in schools.
Sir Michael Bichard thought other sex offenders could slip through the net
Education Secretary Ruth Kelly found herself at the centre of a storm in January when the media reported that several sex offenders were working in schools in England.
The first case to get widespread attention - that of PE teacher Paul Reeve - highlighted how people who were cautioned for sex offences rather than convicted might still be cleared to work in schools.
Mr Reeve was placed on the sex offenders register after he was cautioned by police in 2003 for accessing banned images of children on the internet.
Legally, in accepting a caution, you admit your guilt. But the decision was taken at ministerial level not to put the teacher on List 99 - the list of those barred from working with children. The evidence against him was "inconclusive", officials advised ministers.
He was appointed by a school in Norwich but resigned after eight days when the police raised concerns.
Under the new arrangements, anyone cautioned for a sexual offence is banned from working in schools.
Another case was that of William Gibson, 59, who was cleared to teach by Ms Kelly despite his conviction for indecently assaulting a 15-year-old girl in 1980. Mr Gibson was jailed in 2000 for two-and-a-half years for fraud, forgery and theft.
A maths teacher, he was allowed to work in schools in South Tyneside and Co Durham from 2003 to 2005, but was dismissed when they found out about his conviction.
The Sunday Telegraph published details of a letter from Ms Kelly's department, dated 31 January 2005, in which the teacher was told Ms Kelly had decided "not to bar or restrict " his employment.
Last autumn, Mr Gibson worked at Portchester School in Bournemouth as a supply teacher, but was suspended once his conviction came to light.
He told the Bournemouth Echo: "I am not a paedophile... not a risk to children."
Keith Stuart Hudson, 52, was allowed to work in girls' schools despite being on List 99.
He had been convicted of possessing indecent images of boys.
Former Education Secretary Estelle Morris placed him on List 99 in 2001 with the condition that he could teach only in all-girl schools.
The furore led many to comment that the lessons of the Soham tragedy - where Cambridgeshire schoolgirls Holly Wells and Jessica Chapman were murdered by school caretaker Ian Huntley - had not been acted upon.
Huntley had slipped through the net to get a job at a school in Soham, even though he had been investigated for rape, indecent assault on an 11-year-old girl and sex with underage girls when living in Grimsby.
The Bichard inquiry into Soham found "very serious failings" in the police and vetting system. There were "errors, omissions, failures and shortcomings" which were deeply shocking, it found.
Sir Michael Bichard said the failings meant he could not be sure Huntley was the only person to have "slipped through the net".
He made 31 recommendations, many of which are reflected in the government's new vetting bill.
The government consulted on proposed changes to the vetting system in April 2005 but, despite calls from Sir Michael, had not pushed the changes through by the time the row over the employment of sex offenders broke out in January.
The row led to the announcement of tighter procedures by Ms Kelly - which are set out in the new bill.
At the same time, Ms Kelly was pressed to reveal the number of sex offenders who had been cleared to work in schools.
She admitted 88 people with cautions or convictions for sex offences had not been banned from classrooms, but denied newspaper claims that 150 such offenders were working in England's schools.