Pretoria high court judge Nkola Motata's lawyer, Advocate Danie Dorfling, has criticised the method used to determine the alcohol level in his client's blood samples.
Dorfling told the Johannesburg magistrate's court yesterday that the theorist who developed the "back extrapolation theory" had warned that it was on shaky grounds.
Professor Michael James Stewart used back extrapolations to reach the conclusion that the level of alcohol in the blood samples drawn from Motata was 0,2g/100ml.
According to the theory, biochemists could backtrack the level of alcohol to the time of the accident.
In Motata's case, this was from 0,23g/100ml to 0,26g/100ml when he crashed his car.
However, Stewart did not mention in his statement to the police that the theory had limitations.
Dorfling told Stewart that he did that deliberately to support his opinion.
"Back extrapolation is not recommended," said Dorfling, quoting the theorist.
He said there were many factors that could influence the outcome if using back extrapolation, such as the weight of a person.
Motata is facing charges of drunken driving and defeating the ends of justice.
He allegedly crashed his car into the wall of a Johannesburg home in January last year.
The trial was postponed to September 15.