While currently used criteria for onset of crack propagation in a mixed mode loading situation give different predictions for the angle of incipient branching, the present paper demonstrates that the trajectory of a curved crack to a large extent is independent of the choice among these criteria. The theoretical results have been verified by an analysis of the propagation phase through an incremental description using finite element calculations. A path independent contour integral scheme permitting a separation of the stress intensity factors has proven a powerful tool for the analysis.