In the United Kingdom a person must be told that they are under arrest. They must also be told, in simple language that they can understand, the reasons for their arrest. A person must be 'cautioned' when they are arrested unless this can not be done, for example if the person being arrested is being violent or is drunk. The caution given in England and Wales is: You do not have to say anything, but it may harm your defence if you do not mention when questioned something which you later rely on in court. Anything you do say may be given in evidence.