Para. 40: “It is common knowledge that an expert’s opinion is usually based on his training and experience. In law an expert is permitted to give an opinion on the basis of hearsay information, provided that it relates to specific matters of which he does have personal knowledge. Thus a doctor can give evidence of what he was told by a patient about his condition for the purpose of evaluating his diagnosis; though his testimony is inadmissible to show what symptoms were actually being experienced by the patient; see R. V. Bradshaw (1985) 82 Cr. App. R. 79, CA.”
— Saidykhan v GAMBIA (2010) – ECW/CCJ/JUD/08/10