New Delhi, Sept. 21 -- A supreme irony haunts Bombay House, the headquarters of India's oldest conglomerate. It straddles diverse industries, mostly under a name that has long conveyed 'trust us.' But last week's board vote held by the group's holding company, Tata Sons, has placed its path ahead under a cloud of doubt along with the validity of its board decisions.

In defiance of Noel Tata, the chief of its majority owner Tata Trusts, it approved a third term for N. Chandrasekaran as its chair, even as it resolved to take steps to comply with central bank rules that would mandate a listing of the apex company. Or so it said.

As Tata Trusts argue, Tata Sons' Articles of Association (AoA) require a majority of their own appointed directo...