Half Pass to the Left

In a half-pass, the horse moves with his body forward in a straight line while also moving sideways. If half-passing to the left, for example, the horse will move forward and to the left at the same time. The horse does cross his legs, just as in a side-pass, but not to such a great extent.
To elicit the half-pass to the left, shift your weight to the right side of the horse and apply right leg pressure at the center of the horse’s body. You do not want to reach back to apply leg pressure, which would move the hindquarters, or bring your leg forward, giving instruction to move the forehand. Hold the horse on a straight line by keeping the horse even between the left and right reins. Keep the horse centered between the reins, getting the horse to move sideways on weight shift and leg pressure cues.

Taken from the online course Training Performance Horses