Duress is a defence because the defendant has been effectively forced to commit the crime. It is an excuse based on concession to human frailty. Duress can be either through a direct threat by another or through external circumstances. Duress can be used as defence to all crimes, except murder, attempted murder and, possibly, treason. The defence is only available if the threats to the defendant are aimed at making him commit a specific offence. Threats of violence to make the defendant repay debts did not provide a defence of duress when the defendant decided to commit a robbery in order to obtain the money. In duress of circumstances the defence may be used for any offence which is an appropriate response to the danger posed by the circumstances. Generally, the consent of the victim to an assault where there is no injury is a good defence as it prevents the act from being unlawful.