Scotland has become the first country in the UK to ban outright the physical punishment of children, making it a criminal offence for parents to smack their offspring.

The member’s bill, which was lodged by the Scottish Green party MSP John Finnie and supported by the Scottish National party government, was passed overwhelmingly on Thursday evening, with 84 MSPs voting in favour and 29 against. It is designed to give children equal protection from violence by removing the defence of “justifiable assault” in Scots law.

Parents in England and Northern Ireland are currently allowed to use “reasonable chastisement”, while similar legislation to Scotland was introduced by the Welsh government in March.

Leading the final stage debate, Finnie, a former police officer, said there was an urgent need to bring Scotland into line with best practice across the world, with 57 other countries already prohibiting the physical punishment of children.

Referring colleagues to the substantial body of research highlighting the damaging long-term effects of physical punishment on children, as well as its ineffectiveness as a parenting strategy, Finnie added: “Critics of this simple reform often say that it criminalises parents, but there is no evidence that this change to the law leads to increased prosecutions in any of the more than 50 countries where this change has taken place.”

MSPs also rejected two amendments which the Scottish Conservatives claimed would clarify the bill, in particular around instances such as preventing a child running into a busy road or pulling a pan of boiling water on to themselves.

The Scottish government’s children’s minister, Maree Todd, insisted that the removal of the defence would not affect the ability of parents to use restraint to prevent a child coming to harm, saying there was a difference between an act of restraint and act of discipline but underlining that the purpose of the reform was to give equal protection “with zero qualifications”.

But Oliver Mundell, the Scottish Conservative higher education spokesperson, who spoke for the amendments, said the bill failed to set out clear thresholds for state intervention in family life, arguing: “These concerns about criminalisation have been dismissed throughout the passage of this bill but the truth is no one here can guarantee how this bill will be implemented and interpreted by the police, prosecutors or our courts.”

Children’s campaigners welcomed the move as evidence of a wholesale shift in attitudes to child rearing and children’s rights over the past few decades. Mary Glasgow, the chief executive of Children 1st, Scotland’s national children’s charity, condemned what she described as “scaremongering” during the debating of the bill: “Listening to the evidence from police, social workers and others working directly with families, it has been clear that there is no intent to criminalise parents, but to bring the law in line with the international evidence and modern parenting practice.”

Others warned against complacency. Bruce Adamson, the children and young people’s commissioner for Scotland, said: “The world is watching, and people hope this will inspire other parts of the UK, but we cannot be complacent as there’s much more we can do to put rights-respecting laws in place, like incorporation of the UN convention on the rights of the child [UNCRC] into Scots law.”

In May, the Scottish parliament voted to raise the age of criminal responsibility to 12, but the reform was criticised by some for not raising the age to 14, in line with recommendations from the UN’s committee on the rights of the child.

Likewise, campaigners welcomed Nicola Sturgeon’s commitment to incorporate the UNCRC into Scots law within the next two years, which the first minister made in her keynote speech to the SNP conference in April. However, they have since raised concerns that the legislation is not moving fast enough to be completed before the next Holyrood elections in the the spring of 2021.