I live in a city of over a million people that only has two tracks (both owned by the city and not adjacent to any schools). One Sunday, I show up to the one that's not too far from my home to do some 800s only to find that it's locked up and there's a sign saying that it's under construction (it was to be resurfaced). However, looking over the track, I could see that no construction had begun and no construction workers were present so I decided I might as well hop the fence and do my workout anyways, since it wasn't going to cause any harm. I should mention that people hop the fence all the time and the grounds-workers I've met in the past couldn't care less.
I was on my first or second repeat when some grounds-workers from another field came whizzing up in a golf cart and started yelling and cursing at me that the track is closed and I have to get out. I'm not about to quit in the middle of a workout so, after briefly explaining my views in a civilized tone, I continued with my workout. They left for a few minutes, then came back, saw that I was still there and tried to cut me off with the golf cart, while the old, crotchety guy kept swearing at me. I kept going and eventually they took off for good and went back to the other fields.
I know that legally I was in the wrong, but, as others have said, I couldn't see the guy calling the cops because someone was running on a public track. I kept a lookout nonetheless and, had I seen any officers nearby, I would have hopped back over the fence and taken off. In this case, whether I'm legally right or wrong doesn't really matter (to me) unless I'm standing in front of a judge in court. That was never going to happen and I don't feel like what I was doing was immoral in any way since it wasn't hurting anybody or anything.