Philip Hunter, the chief schools adjudicator, is sceptical about Labour backbenchers' claims that allowing schools to set their own admission policies will mean more selection by ability.
Under the white paper plans, Dr Hunter is getting extra duties. With all 22,500 English schools setting their own admissions policies, as arbiter on disputes over places, he could well need a bigger in-tray.
One of Mr Hunter's biggest concerns is the plan to encourage banded admissions, where schools admit set proportions of pupils from across the ability range. "There would be riots in the streets of many towns and villages on the edges of cities if some of their children had to travel into the city to make way for children travelling in the opposite direction," he said.
"There must be a presumption in favour of giving children places in their local schools, if that is what their parents want."
Banding can only work, he believes, in limited circumstances, where a high-performing school has met local demand but still has spare places.
But he does not fear the prospect of all schools controlling their own admissions, providing the power of local admissions forums to police them is strengthened - something the white paper does not mention.
Schools are encouraged to abide by the admissions code, which bans selection by ability for non-grammar schools and interviewing. Dr Hunter says that schools do follow the code and that most foundation and voluntary-aided schools sought council advice when drawing theirs up.
Labour critics point out that the code is only guidance and schools can legally ignore it. The Government's response is that Dr Hunters' office can force schools to abide by it, placing him firmly in the spotlight.
He says that local admissions forums - committees of school, parent, local authority and church representatives - must review the admissions arrangements of all schools in their areas every year.
The adjudicators' office has never shied away from controversy.
It has cracked down on schools that offer teachers' children preferential treatment. And, in July 2005, adjudicators ordered schools in Kent and Calderdale to stop reserving places for parents who make them their first choice. In the same month three Merseyside Roman Catholic schools were ordered to give priority to children in care.
But its most controversial spat has been with the London Oratory school, where Tony Blair's eldest children were educated.
In 2004 it banned the Catholic secondary from interviewing applicants. The decision was overturned in court and the school won a similar dispute this year, which this time was referred directly to the Secretary of State.
Dr Hunter said that he could not comment on individual cases, but, he said, interviewing introduced "elements of unfairness, lack of independence and lack of objectivity".