Hello Karthik!! Yes..you can do Ba after 12 commerce and its eligibility criteria is to pass 10+2 from a recognised college.After completion of Ba course you can go for LLB which is of 3 years course .But if want to do Law then you can directly get into LLB (5 years course) after completion of our 12th.This way saves your time of 1year and fetch you with two degrees as well.Hope this may helps you.Good luck!!