According to the International Sport Jujitsu Association, Sport Jujitsu:
...consists of five major elements; Ukemi waza (break falling technique), Nage waza (throwing technique), Katame waza (grappling technique), Atemi waza (striking technique) and Katsu waza (revival technique). Therefore a competition that consists of only strikes without grappling is not true sport jujitsu because it is missing a very important element of jujitsu (grappling) which makes it more like a point karate tournament. Also a tournament which consists of only grappling and no striking cannot legitimately be called sport jujitsu because it too is missing a very important element of jujitsu. Without strikes it is only a grappling tournament or often called submission wrestling. A true sport jujitsu tournament represents the art’s totality and consists of all the physical elements.- sort of like MMA without the ground and pound or knee/elbow strikes.
Points are awarded as follows:
1 point for a hand or foot strike to the body
2 points for a controlled kick to the head
2 points for a half throw (where one foot leaves the mat)
3 points for a full throw (both feet leave the mat)
2 points for maintaining a controlled mount for three seconds
4 points for a referee intervention submission (under-belt divisions only)
Automatic win by tap out submission (black belt divisions only)
Strikes to the nose, eyes, groin, spine or against a joint are not allowed. Neither are finger locks, head butts or leg kicks.
The competitions begin much like karate kumite where opponents start standing up and facing each other. The difference is that grappling is as much a part of the game as front kicks and reverse punches are. All the action eventually ends up on the ground. 30 seconds of grappling time is allowed once competitors get there. In the two 2-minute rounds of the competition, if the competitors don't make progress (for example, guards are stalled and no submissions seem eminent), the center judge orders them to their feet. The fight, however is constantly live. In other words, there is no reset that allows everyone time to adjust their gis and gear or get back to the center of the ring. They stand where they are and must be on guard for punches, kicks and sweeps even while returning to an upright position. Competitors are allowed a coach and get 30-second rest between each round.
This explains it better than I can:
Interestingly enough, while hand, mouth, foot and groin protection is worn, black belts do not wear head gear. And the under belts that did had their helmets pulled off during the match anyway. It is intense as all get out, but looked fun as anything. I might give it a go, you never know :-)