An SL(2,C) gauge formulation of a scalar-tensor theory of gravitation is related to the Brans-Dicke theory in the absence of spinorial matter couplings although the natural connection of space-time has a torsion determined by the scalar field. Simplified scaling properties of gravitational variables are elucidated in this geometry. In the presence of matter with intrinsic spin a natural scalar-spinor coupling is exposed. A locally scale invariant limit exists without a Weyl gauge field.