Hey 

Yes, Candidates who have completed their graduation in Distance mode are very much eligible to pursue 3 year LLb courses. But you need to make sure that the institute that you pursued your distance graduation degree is a recognised one. Each college/ University has their own criteria for admission here. Most of them would require you to score a minimum aggregate of 45-50% marks in your graduation degree from a recognised university for admission. Hence as long as your institute is recognised you seem to be eligible to take admission in 3 year law course.

Best of luck