[en] The purpose of this position paper is to reveal, through examples, the potential for collaboration between the theory of legal reasoning on the one hand, and some recently developed instruments of formal logic. Three zones of contact are highlighted. 1. The law of evidence, in the light of labelled deductive systems (LDSs), discussed through the example of the admissibility of hearsay evidence. 2. The give and take of legal debate in general, and regarding the acceptability of evidence in particular, represented using the abstract systems of argumentation developed in logic, notably the coloured graphs of BenchCapon. This is considered through an imaginary example. 3. The use of Bayesian networks as tools for analysing the effects of uncertainty on the legal status of actions, illustrated via the same example These three kinds of technique do not exclude each other. On the contrary, many cases of legal argument will need the combined resources of all three.