In "Of Mice and Men", how was slim like a judge? How did this pass verdict on the dog?

Slim is called "the prince of the ranch". Because of his personality and good judgment, the men respect him. They probably contrast Slim's easy going acceptance of people in contrast to Curley, the bosses son, who is always up tight and looking for a fight. Slim also stands up to Curley, which the men respect. Since he is probably the most respected man on the ranch, his decisions are final. When Candy turns to Slim for help in saving his old dog, Slim simply says that Candy can have the pick of the litter from his dog. By offering Candy a new puppy, Slim is saying it's time to get rid of the old dog. His verdict is the final one, and Candy then allows Carlson to take out his dog and "out it out of its misery."