The suggested summary sentence :
The judge decided who the real owner of the horse was using the horse.
The background story goes as in the following:
Judge: (asking the man) Why did you repay this man’s kindness with your bad ways? Good traveler, the horse is yours.
King: Tell me, how did you know that I was the owner of the horse?
Judge: I had your horse put in a stable next to the court. When the man passed by, the horse never looked up. When you passed, he made a loud sound. It is your horse.
King: (surprised) You are a wise judge! I am the king. I'll make you the High Court Judge in the capital city!
The definition of 'use' is to do something with ~'. In the above passage, it doesn't seem that the judge did something with the horse. To me, "using" in the following summary doesn't seem right. Instead, I think "watching/observing/looking at" sounds more right. What do you think?