Post-Newtonian gravitational radiation reaction for two-body systems

We study gravitational radiation reaction in the equations of motion for binary systems to post-Newtonian order O (v/c) ^2 beyond the quadrupole approximation. The method uses post-Newtonian expressions for energy and angular momentum flux to infinity, and an assujption of energy and angular momentum balance. The equations of motion are valid for general binary orbits. We discuss the coordinate-system dependence of the radiation-reaction formula.