At trial, the judge hears evidence they will use to decide if the accused is guilty. The accused is presumed innocent until proven guilty. It is up to Crown counsel to prove beyond a reasonable doubt that the accused committed the offence or offences. Crown counsel must present all relevant evidence to the judge not just the evidence the points to the accused's guilt. Defence counsel tests the Crown’s evidence and may choose to call other evidence.
In a jury trial, the jury decides whether the evidence supports a conviction and the judge decides any questions of law. In a trial by judge alone, the judge makes all of the decisions.
See What Happens At a Trial to find out more.