Why do we need witnesses? The two witnesses are the official legal witnesses to the marriage under law and their presence serves a legal purpose. The purpose is to be able to swear in court as to the identify of the parties or to testify to the circumstances in which the ceremony was performed, including the date and place. Who can be your witnesses? Anyone can be a witness provided they are over 18 years of age, speak and understand English and are 'relatively' sober. They m