Once you begin the lift, you can not change the position of your body.

Must drive the bar straight up. You cannot have any downward travel on the bar after beginning the lift.

The barbell must touch your chest in a brief hold.

As you drive the bar to complete the movement, you must return the bar to the position you started with your elbows locked and then you can re-rack.

You must lie flat with your head, shoulders, and buttocks in contact with the bench surface. The feet must also be flat on the floor and not be in contact with the bench or its supports. 

You must wrap your thumb around the bar. No reverse or ‘suicide grip‘ is allowed either.

The bar cannot travel downward before reaching the final position. (Once you initiate the up phase off the floor, the bar cannot have any downward movement.)

You must stand erect with shoulders back. (Torso being straight and shoulder blades being retracted.)

You must stand with your knees straight at the completion of the lift. (Along with your torso needing to be erect and shoulders back, your knees must be locked to end the movement.)

You cannot have the bar rest on the thighs during the lift

You cannot step forward or back or move your feet laterally during the "up phase"

You must return the bar to the floor while maintaining control with both hands.

You need to bend your knees and lower the body until the top surface of the leg (upper quad at the hip joint) is lower than the top of the knee.

You need to have your knees locked at both the beginning and end of the movement.

You can’t step forward or backward, or move your feet laterally while squatting.

You can’t touch your elbows or arms with your legs which deliberately supports the movement.

You can’t ‘double bounce’ at the bottom (go up, down, then up again), or have any downward movement of the bar.