Behind Tata-Mistry boardroom clash, a distinct set of governance rules

Tata-Mistry spat has contributed $10 billion decline in market value of group's listed companies

When Ratan Tata retired as chairman of Tata Sons Ltd in 2012, he proposed a change in the laws governing the relationship between India's largest conglomerate and its key shareholder, according to sources familiar with the situation.

Until then, the Tata Trusts — public charities owning two-thirds of the company — had easily protected its investment. A Tata family member had for decades held the chairmanship at both the Trusts and the company, whose businesses include cars, software and steel.

But an outsider, Cyrus Mistry, had just taken the top job at Tata Sons. Tata wanted to make sure the