New Delhi, Sept. 23 -- The unfolding boardroom drama at Tata Sons has, for months, furnished India's business media with an inexhaustible supply of commentary, much of it more interested in personalities than in principle. Yet the episode that precipitated the recent dispute - the Reserve Bank of India's refusal to exempt Tata Sons from its requirement that certain non-banking finance companies seek a public listing - has received remarkably little scrutiny in its own right.

That is a pity, for buried within this obscure corner of financial regulation lies a question of genuine consequence: what, precisely, is the public interest that mandatory listing is meant to serve, and does it survive contact with the entities now being compelled t...