Dear Friend,
First of all, ESI is not a policy; it is an Act/Enactment. There is a scheme under this Act which is mandatory for certain establishments and certain classes of employees based on specific parameters.
From your query, what I feel is that you need to understand this law, its salient features, etc. I advise you to read the ESI Act, and if not that, then at least a guide to employers on Labour Laws by Shri. S R Samant edited by Shri. Chheda recently. You can ask your queries or doubts thereafter. I am sure this forum will definitely address you.
You may also go through the link provided below:
http://www.esic.nic.in/CIRCULARS/ESI...%20English.pdf