What movement causes a slice? The shoulders spinning open, out of sequence, in the downswing, with most of the body weight remaining behind on the right foot.

A set-up in which the ball-position is too far left of centre, or in which the shoulders are open, encourages a slice. A posture which is too upright also tenses up the right shoulder and makes it aggressive enough to start the downswing. Even with the perfect set-up, a certain kind of backswing can also produce a slice. That is, one in which the shoulders are either too tense, or have not been moved out of the way enough. Often backswing weight shift has also not taken place.