The criminal trial is concerned with determining whether a trier of fact (either a judge or jury) can be satisfied beyond a reasonable doubt of an accused's guilt as charged. The beyond a reasonable doubt standard is intended to avoid wrongful convictions and is related to the fundamental tenet of the criminal justice system: the presumption of innocence. The defence is required to do nothing. It is not required to call any evidence whatsoever. The burden remains on the Crown to prove guilt beyond a reasonable doubt. However, a prudent defence lawyer would do all that was within his/her power raise a reasonable doubt.