On Jan. 14, protesters gathered in the northern Indian city of Allahabad and lit candles at the base of a tree trunk, beside portraits of two fathers of the Indian nation.

One, Mohandas Karamchand Gandhi—better known by his honorific, Mahatma (great soul)—is recognizable as the Indian independence activist and icon to peaceful protesters around the world.

The other, however, remains lesser known outside India. He is Bhimrao Ramji Ambedkar, the primary author of the Indian constitution, which came into effect 70 years ago on Sunday. Since December, his image has been held aloft by crowds of demonstrators, who say the ruling Bharatiya Janata Party’s attempts to reform citizenship laws undermine that constitution.

Ambedkar did more than draft the constitution: he was also a revered civil rights leader. Born a Dalit (a social classification formerly called “untouchable,” the lowest position in the Hindu caste system,) he suffered discrimination throughout his life. In 1936, he wrote the influential pamphlet Annihilation of Caste, a blistering argument against the ancient system of social stratification. And when, starting in 1947, he hammered out the Indian constitution’s integral principles of democracy, equality and freedom of religion, he also inserted sections prohibiting caste-based discrimination and legally outlawing the practice of untouchability.