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The Association of Chief Police Officers in Scotland (ACPOS) is to tell a parliamentary committee that the plans could lead to the reporting of thousands of minor incidents, which will have "significant resource implications" for individual forces.
Last night, opposition politicians joined the attack, claiming the proposed Criminal Justice (Scotland) Bill would clog up the procurator fiscal service.
The Scottish Police Federation also expressed concern, warning that already overstretched forces could be swamped by complaints.
ACPOS highlighted its fears in a written submission to the parliaments justice committee, which continues its inquiry into the Criminal Justice (Scotland) Bill today.
The Criminal Justice (Scotland) Bill will make it an offence to smack children under the age of three or hit those of any age with an "implement" such as a belt, slipper or cane, removing the possibility of a defence of discipline or reasonable chastisement.
Parents groups and politicians have accused the Executive of ignoring public opinion by pressing ahead with the smack ban. Critics of the policy fear that even if those who administer "trivial smacks" are found not guilty of assault, they will still face a police and Crown Office investigation.
William Rae, the chief constable of Strathclyde Police and the honorary secretary of ACPOS, said: "Practical difficulties could be experienced in enforcing this legislation, particularly as regards the physical punishment of children under three years of age. It is suggested that this could lead to the most minor of incidents being reported to the police, which could have significant resource implications for Scottish forces."
Roseanna Cunningham, the justice spokeswoman for the SNP, said the huge burden of additional complaints to police could also have an impact on the procurator fiscal service.
She said: "This whole proposal is misconceived from start to finish and it is time for the Executive to realise that.
"Police forces will find themselves swamped with all manner of complaints, many of which will never reach court.
"Unfortunately, the procurator fiscal service will also find itself in a similar position as these complaints filter through."
Lord James Douglas-Hamilton, the justice spokesman for the Conservatives, described the legislation as "unworkable". He said: "You would need closed-circuit television in every house in Scotland to make this work. This will mean a disproportionate amount of police time being spent on matters which will lead to no proceedings."
Jim McDonald, a research officer with the Scottish Police Federation, said: "The Executive may say that they dont intend minor cases to be prosecuted, but who tells the public what a minor case is?
"What concerns us is that there will be a marked increase in complaints, which will all have to be investigated, regardless of how serious they are. "
Jim Wallace, the justice minister, defended the legislation, claiming it was not driven by a desire to prosecute more parents but to help them avoid punishment.
He said: "The policy is intended to achieve a change in attitude and practice to the issue of physical punishment of children. The current lack of clarity in the law makes it difficult for a parent trying to decide whether and how to punish a child within the law.
"Under section 43 of the bill, a parent would at least know beforehand that some actions were certainly illegal."
A poll by the Scottish Parent Teacher Council in February showed 56 per cent of 2,500 parents who responded opposed the plan to outlaw the smacking of children under three, while 83 per cent disagreed with the call by childrens charities to ban smacking altogether. But 94 per cent supported the ban on parents using implements.
Research conducted by System Three, which will go before the committee today, will show greater divisions.
Views on smacking a child under two are evenly split, with 47 per cent saying it should be lawful and 48 per cent saying it should be against the law.
There was much less support for making it against the law to smack a child of four, with 23 per cent against.
However, there was support for a ban on the use of implements to punish a child from 97 per cent of respondents.
When compared to a study conducted in 1991, also by System Three, there is evidence of an increase in support for a smacking ban. Then, 14 per cent thought it should be unlawful to smack a three-year-old, while in the current survey, 23 per cent said hitting a four-year-old should be banned.