Multi-millionaire turned money-launderer Trevor Baines and his wife have lost a legal battle over their committal to a Court of General Gaol.

Sixty-nine-year-old Baines was found guilty last month of money laundering and both he and his wife Wendy were convicted of false accounting. Both will be sentenced next week.

In a legal challenge, the couple claimed the Island's attorney general had overstepped his authority by signing committal papers, because some evidence had been ruled inadmissible.

However, Deemster Kerruish has dismissed the case in the High Court.

Baines was interviewed by American lawyers and his wife Wendy made an affidavit in a civil case about ArtemisSoft, the US company involved in a huge share scam from which Baines was convicted of laundering cash.

Neither knew they were under investigation at the time, so the deposition and affidavit were ruled inadmissible in court before the criminal trial.

The pair argued that the Attorney General shouldn't have given the green light for the case to go ahead because that evidence was flawed.

But Deemster Kerruish, in his judgement, said it wasn't unusual for some evidence put forward by prosecutors to later be excluded from trials, and so the Attorney General hadn't acted beyond his powers.

As the certificate for committal had been issued lawfully, he said he didn't have the authority to overrule it.