Bullet Time(TM) is currently a trademark owned by Take2 interactive. It was bought from Remedy Entertainment and 3D Realms along with the rights to the Max Payne franchise. Bullet Time (TM) is not an accurate concept, but merely an idea used in computer games, where the player could control the flow of time.

Basically it's just a tag on the box. Anyone can still use slow motion and technology similar to Bullet Time. They just can't call it Bullet Time.