In a bid to avoid a drunken driving conviction‚ controversial ANC bigwig Tony Yengeni has called experts to poke holes into the techniques used by the State to nail drunk drivers.But one of his witnesses conceded under cross-examination by the prosecution that she lacked practical experience in the field.Forensic consultant Claire Lewis was supposed to bolster Yengeni’s case but prosecutor Leon Snyman cornered her until she admitted that she only had theoretic knowledge of blood sample analysis.Snyman tore into a report that Lewis handed in to court‚ which sought to highlight discrepancies in the apparatus and methods used by the State to test blood-alcohol levels.Lewis told the court that if Yengeni’s blood-alcohol level was accurately recorded‚ there is no way it would correlate with what the officer who examined him said. The officer said that Yengeni had been found steady on his feet. Lewis said at 0.25% blood-alcohol level Yengeni would have been “heavily intoxicated”.“Therefore the blood-alcohol level system should be queried‚” said Lewis. “The analysis of the sample may have been incorrect.”But Snyman hit back. He dismissed Lewis’ report as flawed and “based on assumption”.“It is biased towards the accused‚” said Snyman.Snyman said Lewis’ evidence is based on theory and she lacked practical experience.A visibly irritated Lewis admitted this but said her business partner‚ Dr Cesarina Edmonds-Smith‚ is more knowledgeable in chemistry.Edmonds-Smith will also be called to testify.Yengeni was arrested in Green Point‚ Cape Town‚ after being pulled over while driving his white Maserati erratically in 2013.Yengeni allegedly drove with a blood-alcohol level of 0.25%‚ five times the legal limit of 0.05%.He is currently out on R500 bail.Coincidentally‚ in 2007‚ Yengeni was also arrested for drunk driving‚ but was found not guilty in the ensuing trial after it was alleged the blood samples had been tampered with.In February this year‚ Sergeant Jonas Gomba‚ who took Yengeni into custody in 2013‚ told the court he had called for back-up after four men tried to obstruct him during Yengeni's arrest."They arrived at the scene and told me I am not allowed to handcuff him‚ asking if I know who this man was. One of them approached me in a threatening way‚" Gomba testified.He said Yengeni was being "riotous"‚ and swore and pointed his finger at him after he was pulled over after nearly hitting a curb.He refused to take a breathalyser test.Yengeni’s counsel Dirk Uijs said his client refused as the kit had not been sealed.Gomba said Yengeni had expressed regret for his behaviour.The case will continue on July 18...