Fishhook / roll stability testing

AB Dynamics explains a steer and counter-steer manoeuvre, which might be applied by a panicked driver avoiding an obstacle in the road. The fishhook test, which remains a requirement for all passenger vehicles sold in the USA, has a steering input defined in terms of angle against time. Maximum severity is achieved by triggering the counter-steer precisely when the maximum roll angle is reached following the initial steer input.