unfortunately, if I prune all the roots on his side of the property, the tree will probably lose stability, and will have to be taken out at that point. it's a big, fat root about 4in in diameter, and we believe one of the main structural anchor root for the tree. Under CA law, unauthorized root pruning encroaching on property is only allowed if it is causing imminent structural damage, but even then not to damage the health of the tree... and there is no damage to neighbor's structure (closest neighbor's structure is 30 ft away, 15ft higher in elevation). so... I attach the photo of the root for those interested, with holes in it that the neighbor claimed to the police it's a damage from a pick axe hitting it.. the pipe you see is a 1in water main pipe to another neighbor's property taht has been sitting exposed to the elements for over year now... the pipe is about 1-1.5ft above the excavated root (hard to judge vertical distance). Neighbor tried to hide the root by putting lots of junk shrubbery and planks around it, but I got a lucky photo shot from right over the fence looking straight down.
