To say that the murder of James Bulger horrified the nation risks understating the impact it had on the country and the way society perceives children.

The grim details of the crime, the age of the perpetrators and their two-year-old victim ensured the case provoked universal grief and anger. The CCTV image of Bulger being led away by the hand became etched in the public consciousness as media coverage of the crime and subsequent trial reached fever pitch. Newspapers sought to reflect the mood of the nation by labelling the killers variously as "evil", "beasts" and "bastards".

The trial and the unbearable suffering it detailed – after being kicked, beaten and stoned, James's body was left on a railway track for his body to be cut in two – were covered in forensic detail. Given the public mood it was no surprise when Jon Venables and Robert Thompson, their identities only revealed after sentencing, were ordered to be detained without limit. Mr Justice Morland said the boys, both 10 at the time of the murder, were guilty of an act of "unparalleled evil and barbarity". Recommending they serve a minimum of eight years, he suggested "violent video films" might be at least partly to blame.

The Guardian leader comment the next day said the chilling murder "unlocked all kinds of primitive fears about the aggressive urges in young children" but warned against James's death being "an excuse for reversing 10 years of criminal justice policy. A system designed to deal with five million crimes must not be steered by one." It also cited the case of Mary Bell, aged 11 when convicted of manslaughter in 1968, as proof that rehabilitation could work.

Lord Taylor of Gosforth, who was lord chief justice, increased the minimum tariff in the Bulger case to 10 years. But that was not enough to dampen the clamour for a tougher sentence. Almost 280,000 people signed a petition demanding that the boys be locked up for good and 20,000 Sun readers completed coupons saying "life should mean life".

In that febrile atmosphere, Michael Howard, who was home secretary, raised it again to 15 years in July 1994 but that was quashed by the House of Lords after judicial review proceedings in 1997. Two years later the European court of human rights (ECHR) ruled that Venables and Thompson did not receive a fair trial and that Howard had breached human rights by intervening to raise the sentences of the killers. Jack Straw, the home secretary at the time of the ECHR ruling, had been preparing to set a new minimum tariff but he handed over responsibility to the lord chief justice in the wake of the judgment. Lord Woolf paved the way for their early release when he ruled in October 2000 that their minimum term had expired, describing the facts of their crime as "exceptionally horrific" but referring to the boys' age at the time as "the one overriding mitigating factor".

After a threat by James's father, Ralph, to hunt down his son's killers, Venables and Thompson won a high court order in January 2001 protecting their anonymity for life once they were freed with new identities. The judge, Elizabeth Butler-Sloss, said she was "convinced that their lives are genuinely at risk as well as their physical safety if their new identities and whereabouts became public knowledge".

In its leader the next day Guardian set out its reasons for declining to join the four newspapers that asked the high court to lift the injunction protecting the anonymity of the killers. The paper noted: "Free speech is important but so is the protection of life … Rehabilitating the two remains the best public protection."

On 23 June 2001 Ralph and Denise Bulger were told of the parole board's decision to release Thompson and Venables, by then both aged 18. The conditions of their licence included a ban on them contacting the Bulger family or each other, or visiting Merseyside without the written consent of their probation officers. The Guardian leader dubbed it "a humane release". "The Bulger family was understandably unhappy with yesterday's decision," it said. "Their lawyers have not helped with their thirst for retribution. They should take note of medical studies, which show some form of forgiveness is needed for scars to heal."

• This article was amended on 7 April 2014 to correct the spelling of Mr Justice Morland's name.