If a defendant could simply claim intoxication as a defence, and be completely exonerated every crook would have a drink before a crime spree, and then, when arrested claim intoxication and be automatically acquitted.

Normal rules of intoxication apply.  Drinking alcohol or taking dangerous drugs, do not provide a defence for usual policy reasons.

R v Rodger & Rose [1998] D’s claimed that they had been forced to escape from prison because otherwise they would have been driven to commit suicide as a result of the extreme depression they were suffering.

Held: For the defence to apply, the "circumstances" had to be external to the actual offender.

Is this truly a logical distinction, however, or is it merely a policy decision based on the peculiar facts of the case? In that respect, it could show the courts reacting as they have done in "necessity" cases, simply on a case-by-case basis.

The court in Rodger and Rose was firmly of the opinion that the subjective approach was not appropriate here.

"We do not consider that such a development of the law would be justified, nor do we think that such an extension would be in the public interest. If allowed it could amount to a licence to commit crime dependent on the personal characteristics and vulnerability of the offender. As a matter of policy that is undesirable and in our view it is not the law and should not be the law"