CATS are STILL invading my back yard....?

I posted a while ago about how to keep the cats out. I tried a few things like the pepper and it did not work. I have a litter box in my back yard. My property is being ruined! Like any blankets we leave out. I have to clean up mounds of poop and pukey hair ...THe neighbor has 24 of the things and she just tells me come get me if they bother you and i will make them stay in the yard. She doesn't believe that they leave her yard! My 2 dogs don't stop the problem. The police said there is nothing to do THERE ARE NO CAT LAWS! Humain Society sais as long as they look fed and healthy they can't do anything....HELP!!!!!!!!!!!!!!!!!!!!!!11…