Traces of cannabis were found in Mr Chisholm's blood

The hearing is considering whether Mark Chisholm should face criminal charges for the crash on 27 June 2002.

The 33-year-old was driving pupils from Largs Academy in Ayrshire to Barcelona when the coach overturned on the A6 near Dijon.

His defence lawyer said the accident was down to human error and not drugs.

There were 51 passengers, including eight adults, on board the coach as it headed to Barcelona.

Katherine Fish, 15, from Largs, died in the accident which left a number of other pupils and staff injured

'Careless driving'

Another pupil, 15-year-old Mark Nicol, lost a hand after his arm was crushed.

Under the French legal system, a person suspected of committing a crime has to be placed under investigation, a step that can lead to criminal charges.

On Friday, a hearing at the Palais De Justice at Dijon considered whether to pursue charges of manslaughter, involuntary injury and careless driving against Mr Chisholm.

The coach crashed on a school trip

Prosecutor Edwige Roux-Combet told the court that Mr Chisholm was personally responsible for the accident.

"It's evident from the analysis experts that THC, the active element in cannabis, was present in his bloodstream at the time of the crash, " she said.

"Even without the drugs there was a serious error.

"There was second sign at the slip road warning drivers to slow to 50 kilometres (31mph) yet evidence shows he was driving at 110 (68mph).

"He should have seen the sign. He didn't see it because there was a lack of vigilance on his part and that is what caused the accident."

Ms Roux-Combet said tests taken two and a half hours after the crash revealed that Mr Chisholm's blood contained 0.61 nanograms of THC per millilitre.

'Human error'

She said that this was not a "negligible amount" and would be enough to impair his reaction speeds and make him careless.

At the time of the accident it was not illegal in France to drive while under the influence of drugs so state authorities in Dijon have been unable to prosecute him for that charge.

But Mr Chisholm's defence lawyer said that the accident was entirely down to human error and the medical evidence suggesting he had smoked cannabis hours before was unreliable.