House expansion issues/rules

Some five to seven years ago, where i live, the rooms at the back of my house used to receive reasonable air and light. Over these years, the neighbours have kept adding to their houses. Now we have reached a situation where the back of the house really seems closed in. I wonder if authorities are really monitoring such residential constructions and what are the rules of expanding that neighbours don’t become affected. For example, is there any ruling on your neighbour installing a window in front of your window, given home privacy issues.