The blind superstar launched legal action last month (Sep15), claiming he shouldn't have to keep paying Johanan Vigoda's widow six per cent of his song earnings following the lawyer's death in 2011.

In his lawsuit, Wonder claimed he trusted Vigoda to present him with a fair contract to sign when he was just 21 years old, but he had no idea the royalties agreement would continue indefinitely and accused his longtime representative of taking advantage of his disability.

However, Vigoda's widow, Susan Strack, is challenging Wonder's allegations, insisting her husband had recruited a witness to read out the contract in full to his client before allowing him to sign, reports

Strack reveals the Superstition star, 65, attempted to have the clause amended years ago, but the dispute was never resolved before Vigoda died. She alleges the contract is therefore still legally binding and is asking a judge to order Wonder to pay up. She is seeking at least $7 million (£4.38 million) in compensation after he halted payments in 2013.