Not that I agree with Tosa fighting or any dog fighting but the photos posted aren't a sanctioned Tosa fight. These dogs are practically g-ds and are treated as such. The posted photos are what I would call a back yard Tosa fight. Not a legal sanctioned fight.

From http://www.bulldoginformation.com/Tosa-inu.html

In Japan dogs are carefully bred and trained and the game is conducted under strict rules and accompanied by holy rituals and processions. The dog fights among Tosa's should never be cruel or bloody and they never end with the death of one of the participants. On the contrary, the fights are designed to last long and, contrary to pit dog fights, a dog that goes for a fast and easy victory, is not considered a good specimen. Similar to Sumo wrestling, the dogs try to bring and hold each other down on the floor. If he dominates for more than 3 min. (or 5 min. if the fight lasted for more than 15 min.) he is declared the winner. A whining or growling dog is declared the loser. The same goes for a dog that turns its hind to the opponent or moves back three steps when attacked. The figth ends in any case after 30 min. in a nil draw if neither of the dogs has proved superior to the other. Unlike most other fighting dog breeds, the original Tosa is conscious of the symbolic value of the fight and it respects the rules of the game and its opponents.
Like sumo wrestlers, the dogs are graded into a hierarchy according to the points they have recently earned. The greatest Tosa "wrestlers" receive the title of Yokozuna, like the famous sumo's.

They are probably the only dogs in the world which are still used quite legally to this day for dog fights. However, the Japanese developed a type of fight according to their mentality that bears no comparison with the notorious pit dog fights held illegally in other parts of the world.