The Supreme Court of India has observed in a case that deviation from normal practice does not necessarily mean negligence. To establish liability, it must be shown that there is a usual and a normal practice; the defendant did not adopt it; and that the course adopted is one that no professional individual possessing ordinary skill would have taken if he was acting with ordinary care. 

Reference

1. Jacob Mathew v. State of Punjab SC / 0457 / 2005 : (2005) 6 SCC 1.