Abstract: Techniques for determining an optimal trajectory for a vehicle are discussed herein. In some cases, the described techniques include receiving, from a first computing system and by a second computing system (e.g., a computing system associated with a trajectory validation system of the vehicle), a primary trajectory and an alternative trajectory for the vehicle. In some cases, the second computing system is configured to select or otherwise determine whether to select the primary trajectory, the alternative trajectory, or neither trajectory for the vehicle. In some cases, the alternative trajectory is determined by applying a lateral swerve to the primary trajectory.