Labour(neighbour) throwing garbage in backyard

My advise is to first resolve amicably. Approach him, explain that it is not right to do so etc politely. That should work in most cases. If it doesn't, warn him of legal consequences. Last resort, do take the help of a legal counsel, record his conduct using pics, witness statements etc and file a case in court with appropriate sections (nuisance, harassment..).

As righly advised the Chaturvidha upayas were prescribed from times immemorial. Sama (request), Bheda (disputes), Dana (incentives) and Danda (punitive) are the ways suggested in scripttures.

Next time make a vedio and photograph when that person is dumping the garbage, show it to owner as good neighbor and then finally make a complaint to police or even file suit.  The neighbors should always maintain good relations and because of servants should not spoil the atmosphere.  There should be compromises and not in these kind of irrational and irresponsible behaviour.  You are a better judge and the remedy through court is always open.