- Protect himself, or another from unlawful use of force (e.g., assault);
- Effect an arrest, or establish physical control of a subject resisting arrest;
- Establish physical control of a subject attempting to flee from arrest or custody;
- Establish physical control of an emotionally disturbed person; and
- Control a dangerous animal by deterring an attack, to prevent injury to persons or animals present.
Or in this slightly longer view, from a different angle.
Or in this video that shows both videos simultaneously