The expert evidence is necessary in the court of law in certain cases in which particular things must be explained in front of the authorities. An expert witness can be helpful because he/she has enough knowledge in his/her area and can explain specific matters related to the case. 

The innocence of an individual accused of crimes in UK stands still until, in a criminal proceeding, the culpability is demonstrated by the prosecution. The right to remain silent is a fundamental principle granted for persons accused of crimes in UK, meaning that the offender doesn’t need to declare if he/she is guilty of crimes or not.