That’s true. Problem is he has a privacy fence that’s below my grade, we are a higher elevation. My yard has an iron fence.
All I can say is that anyone whom is willing to enforce his will on other people’s property should expect to have other people’s will enforced upon his without complaint.
I wish I had read this comment before I posted mine. I am a civil engineer by trade, and whenever I read a story about a person who has a jack@ss for a neighbor, I absolutely salivate when I find out that the jack@ss's home is below the elevation of the law-abiding homeowner.
You have many options to address this in ways that will help solve your problem without a lot of expense.
Gravity is your friend.