Generally, witnesses are not permitted when giving evidence to tender their own opinions as fact. The reason for this is that to allow opinion evidence would be to usurp the fact finding duties of either a jury - in criminal trials - or of the Judge.[1] Thus, a witness is allowed to testify that he saw a suspect waiting on a street corner at a specified time, but not that he believed the suspect 'looked shady', or was 'up to no good'. Such evidence would not only be irrelevant as having little probative value, but could be damaging if accepted by the tribunal as fact.[1]