  Analogies, like precedents, arise within a doctrinal context.  The case at hand raises a legal issue, e.g. does the impersonation of a boyfriend vitiate the victim's consent in the law of rape, is cross-burning protected ‘speech’ within the First Amendment to the US Constitution, does the defence of duress require the defendant to have acted as a reasonable person would have done? Other cases dealing with the validity of consent or the scope of protected ‘speech’ or reasonableness in defences provide potential analogies. An analogy may either be to another case or to another legal doctrine, and the analogy rests on there being some common characterisation of the facts in both cases or the two doctrines which is relevant to the issue. So knives may be analogous to guns if the issue concerns weapons, but knives may also be analogous to teaspoons if the issue concerns cutlery. Duress may be analogous to provocation if the issue concerns defences, but duress may also be analogous to incitement if the issue concerns complicity. Two doctrines or sets of facts are not analogous in the abstract, but in the context of a legal  issue.[17]