The former Cobb County Schools superintendent who attempted to tie the school district up to an Apple laptop contract has refused to testify before a grand jury investigating the deal.

Joe Redden is alleged to have manipulated a contract in favour of Apple.

If it had gone ahead, the $100 million contract would have seen 63,000 portable Macs handed out across the district. Local opponents managed to scupper the plan.

A grand jury has been looking into the case since November 2005.

Redden is filing to have his subpoena to appear before the grand jury quashed, and to have the case curtailed. He maintains the investigation is politically motivated.

Critics of the deal had protested that voters in the state had not been sufficiently consulted for such a major deal to take place.

The state had hoped to finance the scheme through a special sales tax, but a judge later found the state had neglected to tell voters what the money would be used for when the deal was approved by constituents.

Former county commissioner Butch Thompson took legal action that led to the scuppering of the deal.