Loophole allows academies to ignore code designed to block back-door selection.
Academies could escape the most important requirements of the Government's new admissions rules because of a loophole in the wording of the document which came into force this week.
Yesterday, parents of around 1.2million children were told whether they would be offered places in their favoured schools, with as many as a third likely to be disappointed.
The new code could have a dramatic impact on future "offer days", particularly as the number of academies expand dramatically.
The code, designed to prevent back-door selection, has a list of criteria that oversubscribed schools are not permitted to use when deciding which pupils to admit. The bans include prioritising places according to parents'
income, occupation, marital status or educational background - giving preferential treatment to those who made the school their first choice and taking into account the behaviour or attendance of other family members.
The code says these rules apply to "admissions authorities for all maintained schools". But this would not include academies as the document's introduction clearly defines them as being distinct from "maintained schools".
It is a departure from the draft version of the code, consulted on by the Government, which simply stated that "admissions authorities" must not use the banned criteria, wording that would have covered academies.
Margaret Tulloch from Comprehensive Future, the anti-selection pressure group that raised the issue with Jim Knight, schools minister, this week, said: "Words do get lost when documents are drafted, but it seems a little strange that these ones should be added. We didn't get an explanation from him as to why the change had been made. It could allow academies to argue that this doesn't apply to them."
Under academy funding agreements, the education secretary is able to order changes to their admissions policies, to bring them in line with maintained schools. But this is not automatic.
Government figures released this week show that front-door selection has flourished under Labour, with grammar school pupil numbers increasing from 128,712 in 1997 to 155,484 in 2006.
David Chay-tor, Labour MP and Comprehensive Future chair, who requested the figures, said: "We have got welcome improvements to the code, aiming to squeeze various forms of covert selection, but overt selection is expanding rapidly."
The code does say all admissions authorities should "actively promote equity", and Martin Rogers from the Children's Services Network said this requirement could lead to traditional preferences, such as those given to siblings and people living closest to schools, being challenged. The controversy involved in introducing any change to admissions systems was illustrated in Brighton this week (see box, above).
But the Institute for Public Policy Research has called for even more change, recommending that faith, trust and foundation schools and academies should cease to be their own admissions authorities and transfer the responsibility to local councils.
The institute said faith schools that controlled their intakes were 10 times more likely to be highly unrepresentative of the local area than those that did not, while foundation schools were six times more likely to be highly unrepresentative than community schools.
Brighton and Hove, which voted this week to introduce a lottery system for oversubscribed schools, could precipitate a mass bid for foundation status by the city's secondaries.
A knife-edge vote by the local council led to a system that has split the city, prompting demonstrations, petitions and public meetings.
National publicity has centred on the council's decision to use an electronic lottery to decide between applications for oversubscribed schools, rather than deciding by how close prospective pupils live.
But the system centres on geography, dividing the city into six catchment areas, four of which only contain a single secondary, where the lottery would not apply.
Trevor Allen, head of Dorothy Stringer school, has criticised the plan because it would cut off his school from its traditional feeder primaries.
He warned that schools would adopt foundation status, allowing them to become their own admissions authorities and opt out of the council system.
All nine Brighton and Hove secondaries were already considering becoming a federation of foundation schools, partly prompted by discontent at the authority's PFI deal.
Reg Hook, Dorothy Stringer's chair of governors, said: "Any school in the area going for foundation status would make the admissions policy a nonsense. It throws the whole thing up in the air."