1. You should get this person to submit a Witness Statement. Essentially, this person will have relevant evidence as to the arrangement or deal entered into which will bear upon your case. This Witness Statement will then be relied upon by the decision maker in reaching their decision. However, be aware that if the other side wish to cross examine your witness in court, then this person will have to give oral evidence. However, this only arises if the other side decide they need to cross examine this person.