How to counteract a rich guy trying to run you off your land?

[Rob Pattison]

I have a surfing buddy who lives on a bluff on the southern California coast in a house he inherited from his grandparents who bought that house in the 1950's.   The house is worth several million dollars today and has a multi-million dollar view of the ocean from the porch which sits on a bluff and overlooks a portion of the Santa Monica bay.  The house is on a larger lot with a lot of trees and bushes.

Several years ago a rich guy bought one of the houses next door and has been one of those nightmare neighbors from hell.   He's called code enforcement on my friend to remove structures on his property.   He's attempted to move the boundary line.   A bunch of plants on my friend's property suddenly died, then code enforcement showed up and said there was a report from a neighbor that my friend wasn't adequately keeping up his property.

The situation for my friend is so bad, that he feels he can't leave his property for a weekend for fear of what the neighbor would do.  He suspects this guy is trying to run him off his property so that he can buy it up and enlarge his own estate.

I know how I would handle the situation.   Knowing that we are in the People's Republic of California, does anyone have any advice I can relay on what they have done, or would do in a similar situation?