SCs and STs (PoA) Act 1989. This contains the bare Act. Use along with the entire set of files (POA 1 to POA 9) to monitor its implementation using the Right to Information Act 2005 (RTI).
It can also be accessed at http://socialjustice.nic.in/poa-act.php
More on the Act and its implementation can be accessed at the WIKI page: