Allowed to scale a fence to catch a batted ball
1. at the moment of the catch
a) Last point of contact must be in live ball territory
Rule: 1-14 f 1c
A player can climb a fence, or dive over a fence. When the catch is made the player’s last point of contact must be from playable territory and the catch must be made before they contact anything in unplayable territory. If they were a super human they could dive over the fence and make the catch with the entire body over the fence as long as they do not contact the ground or stands on the other side of the fence before the catch.
The following from the ASA supplemental rules is a great explanation of what can occur.
FALLING OVER THE FENCE ON A CATCH.
The fence is an extension of the playing field, which makes it legal for a player to climb the fence and make the catch. When a player catches a ball in the air and their momentum carries them through or over the fence, the catch is legal, the batter-runner is out, the ball is dead, and with fewer than two outs all runners are advanced one base without liability to be putout. Guidelines are as follows:
1. When a player catches the ball before they touch the ground out side the playing area, the catch is legal, or
2. When a player catches the ball after they touch the ground outside the playing area, it is not a catch.
3. When a collapsible, portable fence is used and a defensive player is standing on the fence when the catch is made, it is a legal catch. A defensive player may climb a fence to make a legal catch; therefore a defensive player should also be able to stand on a fence that has fallen or is falling to the ground. As long as the defensive player has not stepped outside the playing area, the other side of fence, the catch is legal.