The prosecution must always prove that a defendant is guilty beyond reasonable doubt. The defendant does not have to prove that she or he is not guilty.
The defendant does not have to present any evidence. She or he may attempt to show any inconsistencies and shortcomings in the prosecution case and simply argue that the prosecution has not proved her or him guilty beyond reasonable doubt. If this is accepted the defendant will be found not guilty.
The defendant however, may go into the witness box to give evidence on oath or affirmation, they will then be cross-examined. They are also able to call other witnesses on her or his behalf. The defendant may choose not to give evidence personally but call other witnesses. There are a number of different defences that may be put forward. If appropriate the defendant may rely on more than one defence, see CRIMINAL AND TRAFFIC OFFENCES, Defences.