We dedicate this article to the memory of Jean-Claude Paumier. Abstract. This work is concerned with the frictional contact problem governed by the Signorini contact model and the Coulomb friction law in static linear elasticity. We consider a general finite-dimensional setting and we study local uniqueness and smooth or nonsmooth continuation of solutions by using a generalized version of the implicit function theorem involving Clarke's gradient. We show that for any contact status there exists an eigenvalue problem and that the solutions are locally unique if the friction coefficient is not an eigenvalue. Finally we illustrate our general results with a simple example in which the bifurcation diagrams are exhibited and discussed.Introduction. Friction problems are of current interest both from the theoretical and practical point of view in structural mechanics. Numerous studies deal with the widespread Coulomb friction law [6] introduced in the eighteenth century which takes into account the possibility of slip and stick on the friction area. Generally the friction model is coupled with a contact law, and very often one considers the unilateral contact allowing separation and contact and excluding interpenetration. Although quite simple in its formulation, the Coulomb friction law shows great mathematical difficulties which have not allowed a complete understanding of the model. In the simple case of continuum elastostatics (i.e., the so-called static friction law) only existence results for small friction [24,19,9]) as well as some examples of nonuniqueness of solutions for large friction coefficients [14,15]. As far as we know there does not exist any uniqueness result and/or nonexistence example for the continuous model.In the finite-dimensional context, the finite element problem admits always a solution which is unique provided that the friction coefficient is lower than a critical value vanishing when the discretization parameter h tends to zero (see e.g., [10]). In fact the critical value behaves like h 1/2 . Actually, it is not established if this mesh-size-dependent bound ensuring uniqueness represents a real loss of uniqueness or if it comes from a "nonoptimal" mathematical analysis. In particular we don't know if for a given geometry there may exist a mesh and a nonuniqueness example for an arbitrary small friction coefficient. Several examples of nonunique solutions exist for the static case involving a finite or infinite number of solutions (see, e.g., [13]). Moreover it is possible to find (using finite element computations) for an arbitrary small friction coefficient a geometry with a nonuniqueness example (see [12]).Our aim in this paper is to propose and to study a framework for the finite-dimensional problem in order to obtain results ensuring local uniqueness and smooth or nonsmooth continuation of solutions. As far as we know the only existing results concerned with uniqueness in the finite-dimensional case are global and assume that the friction coefficient is small. As a consequence t...