A note on the Gannon-Lee theorem.

We prove a Gannon-Lee theorem for non-globally hyperbolic Lorentzian metrics of regularity C 1 , the most general regularity class currently available in the context of the classical singularity theorems. Along the way, we also prove that any maximizing causal curve in a C 1 -spacetime is a geodesic and hence of C 2 -regularity.