The Supreme Court of India laid down several principles in the case of B. Karunakar v. Union of India (1993) related to the conduct of departmental inquiries and the principles of natural justice. These principles include:

1. The charge-sheet must be specific: The charge-sheet issued to the employee must be specific, and the employee must be given adequate details of the charges against them.
2. The employee must be given a reasonable opportunity to reply: The employee must be given a reasonable opportunity to reply to the charges against them, and their reply must be considered by the inquiry officer.
3. The inquiry officer must be impartial: The inquiry officer must be impartial and unbiased, and must not have any personal interest in the case.
4. The employee must be allowed to cross-examine witnesses: The employee must be allowed to cross-examine the witnesses against them, and the inquiry officer must ensure that the cross-examination is conducted in a fair and reasonable manner.
5. The inquiry officer must record reasons for their findings: The inquiry officer must record the reasons for their findings, and the findings must be based on evidence that has been properly tested and evaluated.
6. The employee must be given a copy of the inquiry report: The employee must be given a copy of the inquiry report, and must be allowed to make a representation against the report before a decision is taken.
7. The decision-maker must be fair and impartial: The decision-maker must be fair and impartial, and must not have any personal interest in the case.

Overall, the B. Karunakar case emphasized the importance of conducting departmental inquiries in accordance with the principles of natural justice and ensuring that employees are given a fair opportunity to present their case. The case also highlighted the importance of impartial inquiry officers and decision-makers and the need for transparency and accountability in the inquiry process.