1. there is no such separate provision for issuing medico legal certificate. if you visit a public hospital?OPD the treating doctor would issue the medical certificate stating the reason of injury on the body of it.
2. You can visit the hospital as many times as you want provided in each such occasion there is fresh injury,
3. Only in the vent of grave injury making the victim unconscious the Police comes into play.
4. No such certificate can be issued in the case of old injury , more so, the wound is not visible any more.