Will the privacy laws be affected by installing cctv outside flat?

We live in a housing society in Mumbai. We have troublesome neighbours incidentally one of them is a lawyer whose only job is filing complaints and cases against housing society. The neighbours have been throwing filth and flooding the passage outside our house with water. They indulge in such acts when the doors are closed. We intend to install cctv cameras so that we can catch the culprits redhanded. Is it legal to install cctv cameras outside our flat so that only the area outside our flat is covered. We will inform the society about it. Can the neighbours raise an objection to it? Since the privacy laws are not clear how can a person make use to cctv technology to protect oneself from such miscreants and mischief makers.