A cautionary note from the Privy Council on the timing of a challenge to the defendant's fitness to stand trial: Taitt v The State (Trinidad and Tobago)  UKPC 38, at :
 UKPC 2, para 68 the Board expressed its concern at the fact that reports as to the appellant's ability to instruct counsel were produced ex post facto and without any explanation as to why medical evidence on the issue of fitness had not been produced in the courts below. It wished to make clear that it should not be assumed that even highly persuasive evidence produced for the first time at the final appeal stage would be admitted: para 70. The fresh evidence has been admitted in this case so that it may be scrutinised. But the Board is just as anxious to make it clear that it will only be in an exceptional case that it will entertain the argument that the appellant was not fit to stand trial because he is of low intelligence due to a learning disability when the point was not taken on his behalf by counsel at his trial. It is the responsibility of counsel to assess whether his client is fit to stand trial. He is in the best position to judge at first hand whether his client is able to understand the charge that has been brought against him and to give instructions for his defence. His conclusion that his client is fit to plead will normally be given great weight. The Board will not permit the introduction of the issue for the first time at the final stage unless the evidence points very clearly to the fact that there has been a miscarriage of justice."