Lance Technique - Lateral
Correct lateral lance technique
The lateral angle of your lance will be fixed for the duration of your pass. It will not rotate sideways as you raise and lower the lance. It is the timing of the vertical angle of the lance -- not the lateral angle -- which allows it to hit your opponent while not hitting your opponent's horse.
Before you begin, position your lance so that when lowered it will cross the neck of your horse at the angle needed to strike your opponent.
Keep your lance at the same angle throughout the pass, so that you are lowering and raising the lance in a single plane. Maintain the angle of the lance and the position of your horse near the tilt as you lower the lance, strike the ecranche (shield) of your opponent, and return the lance upright.
Incorrect lateral lance technique (rotation)
If you start the pass with the lance parallel to the tilt on your right side, you will find yourself adjusting the position of the lance mid-pass in order to strike the target which on your left. This frequently results in over-rotating the lance into your opponent as they pass you, and requiring that you target on both vertical and lateral planes.
Such a strike is also more likely to result in lance damage beyond the tip as the more solid portions of the lance are likely to connect with your opponent, as you will have established rotating momentum. This increases the chance of a tube / ferrule strike against your opponent, or the lance "skipping" off the far side of your opponent and causing you to lose control of your lance entirely due to the resulting torque.
When incorrect lateral technique (starting the pass with the tip of the lance to the right of your horses head) is combined with incorrect vertical technique (lowering the lance too soon) the potential for striking your own horse in the head increases significantly.
Incorrect lateral lance technique (reaching)
If your horse and your lance are in the correct place and your opponent is not, do not attempt to fix your opponent's mistakes. Reaching for your opponent (by over-rotating) interrupts the motion of your horse by introducing rotation, increases the chance of you losing control of your lance (due to the increased angles and risk of the lance skipping off the far side of your opponent) and trains you and your horse in incorrect lance technique.
(an animated illustration for the correct lateral technique is in-progress but not finished yet)