Hey Shibin.

This is a very absurd choice and moreover the eligibility for persuing 3 year LLB is:

The candidate must have completed the Bachelors degree program from a recognized University with a minimum of 45% aggregate marks.

Admission are based on either entrance exam or marks obtained in the qualifying exam, whatever the admission norms of the Institution of concern. Some of the Universities considers candidates with a minimum of 50% aggregate marks in the qualifying exams.

Candidates who have completed their Bachelors degree from a recognized University through distance mode are also eligible. However, candidates who have obtained Bachelors degree directly without having passed the +2 level of exam or any basic qualification for prosecuting such studies are not eligible for admission in the law courses.

LLB is not a side course which one can opt besides any other bachelors program. 

Hope this helps. All the best.