This post is slightly late but relates to an interesting development in Singapore. In May 2014, the Singapore Court of Appeal issued interesting observations about witness body language (here). While those observations were made in the context of a civil case, they will be particularly relevant for criminal cases. Citing scientific studies on how nervousness is often misinterpreted as deceitfulness, the court held: “Put simply, therefore, the demeanour of a witness on the witness stand is not invariably a conclusive indicator of deception. ”
An insightful media report on this by Andy Ho may be found here.