Chronology protection in stationary 3D spacetimes

We address chronology protection in stationary, rotationally symmetric spacetimes in 2+1 dimensional gravity, focusing on the case of negative cosmological constant. We show that, if such spacetimes contain closed timelike curves, they belong to one of the following two classes: (i) bad asymptotics: the boundary itself contains closed timelike curves, or (ii) unphysical stress tensor in the bulk: the matter stress tensor violates the null energy condition. We illustrate these properties in a class of examples involving rotating dust in anti-de Sitter space and comment on the use of the AdS/CFT correspondence to study chronology protection.