Quorum

A quorum is the minimum number of members of a group necessary to constitute the group at a meeting. In a deliberative assembly, a quorum is necessary to conduct the business of that group. In contrast, a plenum is a meeting of the full body. A body, or a meeting or vote of it, is quorate if a quorum is present.
The term quorum is from a Middle English wording of the commission formerly issued to justices of the peace, derived from Latin quorum, "of whom", genitive plural of qui, "who". As a result, quora as plural of quorum is not a grammatically well-formed Latin-language construction. In modern times, a quorum might be defined as the minimum number of voters needed for a valid election. Quorums are often part of parliamentary procedure.

In ''Robert's Rules of Order''

According to Robert, each assembly determines the number of members that constitutes a quorum in its governing documents. The quorum may also be set by law. Robert's Rules of Order Newly Revised states that the quorum set in an organization's bylaws "should approximate the largest number that can be depended on to attend any meeting except in very bad weather or other extremely unfavorable conditions."
In the absence of such a provision, a quorum is an assembly whose membership can be determined is a majority of the entire membership. In the meetings of a convention, unless provided otherwise, a quorum is a majority of registered delegates, even if some have departed. In a mass meeting or in an organization in which the membership cannot be accurately determined, the quorum consists of those who attend the meeting.
In committees and boards, a quorum is a majority of the members of the board or committee unless provided otherwise. The board or committee cannot set its own quorum unless given such power. In a committee of the whole or its variants, a quorum is the same as the assembly unless otherwise provided.
In online groups, a quorum has to be determined in a different manner since no one is actually "present". The rules establishing such groups would have to prescribe this determination. An example is that a quorum in such groups could be established as "present" if enough members state that they are "present" at the designated meeting time.

Determination of a quorum

The chairperson of the group has the responsibility to determine if a quorum is present. In addition, any member can raise a point of order about an apparent absence of a quorum. Because it is difficult to determine exactly when a quorum was lost, points of order relating to the absence of a quorum are "generally not permitted to affect prior action; but upon clear and convincing proof, such a point of order can be given effect retrospectively by a ruling of the presiding officer, subject to appeal."

Limited actions in the absence of a quorum

When a quorum is not met, the assembly can take only limited procedural actions. These limited actions are to fix the time to which to adjourn, adjourn, recess, or take measures to obtain a quorum, such as a motion that absent members be contacted during a recess.
Any other business that is conducted is not valid unless it is ratified at a later meeting where a quorum is present. However, there is no obligation to ratify such action and those responsible may be punished for their actions.

Call of the house

In legislatures and other assemblies that have the legal power to compel the attendance of their members, the call of the house procedure may be used to obtain a quorum. This procedure does not exist in ordinary societies, since voluntary associations have no coercive power.
When a call of the house is ordered, the clerk calls the roll of members and then the names of absentees. Members who do not have an excused absence are arrested and brought in. The arrested members may be charged a fee.
Both chambers of the United States Congress have the power to compel the attendance of absent members; this procedure, authorized by Article I, Section 5 of the U.S. Constitution is rarely used in the modern Congress.

No-show paradox

Quorums have been criticized by social choice theorists for their pathological behavior, including an absurd result called a no-show paradox, where a proposal may pass because too ''many'' members oppose it. This has led many jurisdictions and bodies to replace traditional quorums with quorums of votes in favor, i.e. a requirement that any proposal be supported by a certain share of the entire membership to pass.

By country

Australia

While Section 22 and section 39 of the Constitution of Australia set the quorum for sittings of the House of Representatives and Senate at one-third of the whole number of MPs and senators, respectively, Parliament is permitted to change the quorum for each House by ordinary legislation.
In the House of Representatives, the quorum was amended down to one-fifth by the House of Representatives Act 1989, which means the quorum of the current House of 151 MPs is 31 MPs. In the senate, the quorum was amended down to one-quarter by the Senate Act 1991, so 19 senators is a quorum. The quorum includes the occupant of the Chair, and is not reduced by the death or resignation of a member or senator.
If at the beginning of a sitting the quorum is not met, the bells are rung for five minutes and a count is then taken; if the quorum is still not met the sitting is adjourned until the next sitting day. During the sitting, any MP or senator may draw attention to the lack of quorum in which the bells are rung for four minutes, and if a quorum is still not met the sitting is adjourned.
Although quorum-busting is virtually unheard of in Australia, it is not unknown for parties to deliberately use quorum counts as a disruptive tactic and there have been some suggestions to enact rules to restrict this practice; however, this is very difficult due to the explicit mention of a quorum in the constitution. It is considered disorderly to call attention to quorum when one exists, and members or senators who do so can be punished.

State and territorial quorums

State/Territory	Legislative Council	Legislative Assembly / House of Assembly
New South Wales	9	21
Victoria	One-third	21
Queensland	N/A	17
Western Australia	one-third + President	one-third + Speaker
South Australia	10	17
Tasmania	7	14
Australian Capital Territory	N/A	majority
Northern Territory	N/A	10

Austria

In the National Council of Austria at least one-third of the representatives must be present, so that they may decide on a simple law. At least half of the members must participate if a constitutional law should pass the parliament. Over and above that, constitutional laws require the consent of at least two-thirds of the members present.

Canada

In Canada, the Constitution Act, 1867 sets quorum for sittings of the House of Commons of Canada at 20 MPs. If a member calls for quorum to be counted and a first count shows there are fewer than 20 members, bells are rung to call in the members; if after 15 minutes there are still fewer than 20 members, the session is adjourned to the next sitting day; the members present sign a roll on the table of the house, and this list is included in the Journal of the House. There is no need for quorum when the attendance of the House is requested in the Senate of Canada, for example, when royal assent is being given to bills. The quorum of the Senate is 15.

Provincial and territorial quorums

Province/Territory	Quorum
Alberta	10
British Columbia	10
Manitoba	10
New Brunswick	14
Newfoundland and Labrador	15
Northwest Territories	majority
Nova Scotia	15
Nunavut	majority
Ontario	12
Prince Edward Island	10
Quebec	21
Saskatchewan	15
Yukon	majority

Germany

In the German Bundestag more than half of the members must be present so that it is empowered to make resolutions. It is however common that fewer members are present, because they can still make effective decisions as long as no parliamentary group or 5% of the members of the parliament are complaining about the lack of quorum. This, in rare cases, is used by opposition parties to delay votes.

Hong Kong

Article 75 of the Basic Law of Hong Kong stipulates that the quorum required for the meetings of the Legislative Council of Hong Kong as "not less than one-half of its members". Between 1997 and 2012 the quorum was 30, and since 2012 it has been 35. Prior to 1997 transfer of sovereignty over Hong Kong, the quorum was set at 20.
The quorum for the panels, committees and subcommittees is, nevertheless, one-third or three members, whichever the greater, as according to the Rules of Procedure. The three standing committees, namely, the Finance Committee, the Public Accounts Committee and Committee on Members' Interests, is exceptional that the quorums are 9, 3 and 3 respectively.

India

of the Constitution of India stipulates that at least 10% of total number of members of the House must be present to constitute the quorum to constitute a meeting of either House of Parliament. For example, if the House has the total membership of 250, at least 25 members must be present for the House to proceedings with its business.
If at any time during a meeting of a House there is no quorum, the chairman has to either adjourn the House or suspend it until there is a quorum.