There's an old saying: Give a man a fish and he eats for a day, teach a man to fish and he eats for a lifetime.
My dilemma involves drawing a fine line between giving you the fish and teaching you to fish.
I sometimes forget that people who come here with questions don't have the experience that I have so let's see if I can steer you in the right direction.
You're correct that the three cases don't actually "define" abuse of judicial discretion. Indeed, one of them (Booker) doesn't even use the words although the other two do.
However, all three address what a judge did or didn't do and you can infer the definition of abuse of judicial discretion by what the judge did or did not do and whether the appellate court reversed or did not reverse his decision.
So, in the interest of teaching you how to fish, please re-read all three decisions and let's test your analytical prowess.
In each case take the following steps:
1 - Determine the limitations on the trial judge's discretion. (Hint - His discretion is his ability to make decisions as he sees fit.)
2 - Determine if the trial judge strayed from those limitations.
3 - Determine if the appellate court agreed or disagreed with his decisions.
In each of the three cases writing down the answers to those three questions shouldn't take more than a few sentences each.
Once you have answered those three question for each case, then give me what you think is the definition of abuse of judicial discretion.
Here are the complete decisions for all three cases:
BURNS v. UNITED STATES.
UNITED STATES V. BOOKER
GALL v. UNITED STATES