Dear Naresh,
When a candidate applies for any post, he/she must be ready for his/her candidature getting turned down (not rejected, please note). Against this backdrop, if your candidature, if turned down, does not mean that your worth gets reduced. The mismatch between the candidate's profile and the expectations of the interviewer are common. Therefore, do not lower your spirit.
Though you have acquired a degree in law, you do not have practical exposure to statutory compliance. But then there are thousands of HR professionals like you. Anyway, try to improve your knowledge of labour laws. Secondly, if you are weak in statutory compliance then you may not search for a job in the manufacturing sector. You may search in the service industry.
Coming to doubt being raised on your LLB degree. The doubt could have been raised because of the lack of exposure to the legal field. Since you have not worked in the legal department, a doubt might have been raised. Nevertheless, after acquiring a professional field like law or any other field, one has to remain in touch with that field. This can be done by reading magazines, books, articles etc. Have you done that?
When the students study for some professional course, they just study for acquiring a certain percentage or class. Once they get the degree, the books remain closed. However, a little do they realise that a professional's real journey begins after acquiring the degree and not before.
The person also should be recognised by the way one carries oneself. In regular dealing, whether the person uses the terminology of a particular field or not matters a lot. I have seen a large number of MBAs who hardly can be called MBAs because of their inability to differentiate from non-MBAs.
Lastly, please note the English proverb, reading maketh a man. After reading, you should be able to express that knowledge in day to day life as well. No problem, take failure as a lesson. Work hard. You will succeed.
All the best!
Dinesh Divekar