Here is the fetch over high jump requirement for dogs earning the Schutzhund 3 title:
8. Scaling a 1.8m high 1.5m wide fence off the leash and retrieving an object belonging to the handler (15 points)
The fence has two sloping sides measuring 1.9m in height and 1.5. in width, each fitted with three rungs measuring 24 mm by 48 mm on the outside surface. The distance between the bases of the two sides must be calculated so that the summit of the fence is 1.8m above the ground (measure at a right angle to the ground).
The handler takes up position in front of the fence at a suitable distance from it. His dog sits at his heel, off the leash.
The handler may throw any object the dog can carry over the fence instead of a personal possession if he so desires. On being given the audible commands “Jump” and “Fetch” the dog must scale the fence, quickly seize the object, climb back over the fence and sit very close to the handler, facing him. It must hold the object for a few seconds and then, in response to the audible command “Give”, return it to the handler. On the audible command “Heel” the dog must sit down immediately at the handler’s heel.
The audible command “Fetch” must given before the dog reaches the object.
This dog is a police dog. Ergo he has gone over many more extremely high fences/walls (slippery 1s, too!) than even the standard schutzhund. They have to scale wood or painted concrete barriers - NOT "sloped" such as schutzhund, but normal every-day vertical barriers. No traction.
A chain-link fence of only 6' is asking for trouble. I agree that it would've been better to have a ceiling fence on it. However, I still don't know that I'd sue the place. How could they know?