Article 108 provides for a Joint sitting of both Houses Lok Sabha and Rajya Sabha in certain cases:

When a Bill other than a Money Bill or a Constitution Amendment Bill, has been passed by one House and transmitted to the other House—

(a) the Bill is rejected by the other House; or 

(b) the Houses have finally disagreed as to the amendments to be made in the Bill; or 

(c) more than six months elapse from the date of the reception of the Bill by the other House without the Bill being passed by it,

The President may, unless the Bill has lapsed by reason of dissolution of Lok Sabha,

• Notify the Houses by message, if they are sitting, or 
• By public notification, if they are not sitting, 

his intention to summon them to meet in a joint sitting 

This provision is only an enabling one, empowering the President to take a step for resolving a deadlock between the two Houses.

It is not obligatory upon him to summon the Houses to meet in a joint sitting.

Moreover, this provision does not disable the receiving House from passing the Bill after the lapse of six months, provided the Bill has not lapsed by reason of dissolution or the President has not already notified his intention to convene a joint sitting.

When the President has notified his intention of summoning the Houses to meet in a joint sitting, neither House shall proceed further with the Bill. 

President may thereafter issue an order summoning the Houses to meet in a joint sitting for the purpose of deliberating and voting on the Bill on a date which is suggested by the Prime Minister or the Prime Minister in consultation with the Cabinet and agreed to by the Speaker, and if he does so, the Houses shall meet accordingly.

Once the President has notified his intention to summon the Houses for a joint sitting, dissolution of Lok Sabha shall not stand in the way of proceeding with the Bill at a joint sitting 

Procedure at Joint Sitting— At a joint sitting, The Speaker presides, and the Secretary-General, Lok Sabha acts as Secretary-General of the joint sitting.

During the absence of the Speaker from any joint sitting, the Deputy Speaker of Lok Sabha or if he is also absent, the Deputy Chairman of Rajya Sabha or if he too is absent, such other person as may be determined by the members present at the sitting, presides.

The quorum to constitute a joint sitting is one-tenth of the total number of members of the two Houses. 

If at a joint sitting of the House, the Bill referred to it, with such amendments, if any, as are agreed to in joint sitting, is passed by a majority of the total number of members of both Houses present and voting, it is deemed, for the purposes of the Constitution, to have been passed by both Houses.

At a joint sitting, no amendment can be proposed to the Bill other than 

• such amendments, if any, as become necessary by the delay in the passage of the Bill and 
• such other amendments as relate to matters with respect to which the Houses have not agreed. 

The decision of the person presiding as to the admissibility of amendments is final. 

At a joint sitting, the Speaker, or the person acting as such, shall not vote in the first instance, but shall have and exercise a casting vote in the case of equality of votes. 

How many joint sittings are held until?

So far, three joint sittings have been held under Article 108. 

The first occasion arose following a disagreement between the two Houses over certain amendments to the Dowry Prohibition Bill, 1959.  The joint sitting was held in the Central Hall of Parliament House on 6 May 1961, followed by another sitting on 9 May 1961 when the Bill, as amended, was finally passed. 

The second occasion arose following the rejection by the Rajya Sabha of the Banking Service Commission (Repeal) Bill, 1977. The joint sitting of the Houses was held on 16 May 1978 in the Central Hall of Parliament House for the purpose of deliberating and voting on the Bill and the Bill was finally passed.

The third joint sitting was held on 26 March 2002 when the motion to consider the Prevention of Terrorism Bill, 2002, seeking to replace the Prevention of Terrorism Ordinance (POTO) as passed by the Lok Sabha was rejected by the Rajya Sabha. This sitting was held for the purpose of deliberating and voting on the Prevention of Terrorism Bill, 2002 and the Bill was finally passed.