The joint sitting of the Lok Sabha and the Rajya Sabha is summoned by

Article 108 of the Constitution of India provides a mechanism to resolve a deadlock between the Lok Sabha and the Rajya Sabha over an ordinary (non-money) bill: a joint sitting of both Houses. The power to summon this joint sitting is vested exclusively in the President of India, exercised through a notification issued for that purpose.

Applying this here: when the two Houses disagree on a bill, or one House rejects it, or more than six months pass without action by the other House, Article 108(1) lets the President notify the intention to summon a joint sitting, and it is the President — and only the President — who then actually summons both Houses to meet together under Article 108(3). This provision has been invoked only three times in India's parliamentary history: the Dowry Prohibition Bill (1961), the Banking Service Commission (Repeal) Bill (1977), and the Prevention of Terrorism Bill, 2002 (POTA).

• the Speaker of the Lok Sabha presides over a joint sitting once it has been summoned, but presiding is not the same power as summoning it — that authority belongs to the President alone.

• the Parliament (the two Houses together) is the body that meets in the joint sitting; it cannot summon its own extraordinary sitting — a specific constitutional office does that.

• the Chairman of the Rajya Sabha presides only over the Rajya Sabha's own sittings and has no role in convening or presiding over a joint sitting of both Houses.