Notice period is given in some laws.
For example Bombay Shops and establishment lays down:
1. Notice of termination of Service: Notice of termination will be governed as under:
a) Upto 3 months of Employment: NIL.
b) More than 3 months: 14 days notice in writing (or wages in lieu thereof).
c) Employment one year or more:- at least 30 days notice in writing (or wages in lieu thereof).
But most of the cases,the job offer/appointment letter lays down the notice period to be observed.