While notionally every Act of the Oireachtas must receive assent of both chambers, in practice the Seanad can only delay rather than veto decisions of the Dáil.

The fact that 11 senators are appointed by the Taoiseach usually ensures that the Government, which must have the support of the Dáil, enjoys at least a plurality in the Seanad.

In 1919 Irish nationalists established a legislature called Dáil Éireann but this body was unicameral and so had no upper house.

11) Act 1929 by filling of vacancies by vote of both Dáil and Seanad, the system that continues today for panel members.

The new system of vocational panels used to nominate candidates for the Seanad was inspired by the corporatist Roman Catholic social teaching of the 1930s and, in particular, the 1931 papal encyclical Quadragesimo anno.

In that document, Pope Pius XI argued that the Marxist concept of class conflict should be replaced with a vision of social order based on the co-operation and interdependence of society's various vocational groups.

There are also allegations of patronage in the selection of its members, with senators often being close allies of the Taoiseach or candidates who have failed to be elected to the Dáil.

The Seventh Amendment in 1979 altered the provisions of Article 18.4 to allow for a redistribution of the university seats to any other institutes of higher education in the state.

[12] On 31 March 2023, following a direct appeal on the point of university graduates voting, the seven-judge Supreme Court ruled in Heneghan's favour and struck down provisions of the Seanad Electoral (University Members) Act 1937 limiting the right to vote to NUI and Trinity College graduates.

The legislation also replaces Seanad by-elections for the six seats with a list system mirroring the process used in European Parliament elections and increases the number of nominations a prospective candidate needs from 10 to 60 registered electors or the payment of a deposit of €1,800.

[15] Following agreement between Fianna Fáil, Fine Gael and a group of independent TDs to form a new government in January 2025, the programme for government, published on 15 January, committed only to implementing the 2024 Act,[16] which reflected Fianna Fáil's 2024 election manifesto pledge.

Taoisigh have often included people from Northern Ireland among their eleven nominees, such as John Robb (served 1982–1989), Seamus Mallon (1982–1983) of the SDLP, Bríd Rodgers (1983–1987) also of the SDLP, peace campaigner Gordon Wilson (1993–1997), businessman Edward Haughey (1994–2002), Maurice Hayes (1997–2002), and Emer Currie (2020–2024).

Niall Ó Donnghaile was elected in April 2016 as a Sinn Féin senator for the Administrative Panel while serving on Belfast City Council.

Ian Marshall, a farmer and activist from a Unionist background, was elected to the Agricultural Panel in a by-election in April 2018.

[23] Mal O'Hara of Belfast, leader of Green Party Northern Ireland, was deemed elected on the Administrative Panel in 2024.