What parliament does
What you are choosing when you elect 400 deputies and 200 senators: what powers the two chambers have, what the 2020 reduction changed, and why a member can switch group.
What are you electing on polling day?
The two chambers of parliament: 400 deputies and 200 senators.
They pass the laws, approve the budget, authorise the ratification of international treaties, set up committees of inquiry and, sitting jointly, elect the President of the Republic. You are not electing the Prime Minister, who is appointed by the President and must then win the confidence of both chambers.
Source: Art. 55 of the Constitution
Do the Chamber and the Senate do different things?
No: they have identical powers. This is what is called perfect bicameralism.
The legislative function is exercised jointly by the two chambers: a law must be approved by both in exactly the same text, and a government must hold the confidence of both. The differences are in size and in how seats are shared out — the Senate is elected on a regional basis, with a minimum of three senators for each Region or autonomous Province, two for Molise and one for Valle d’Aosta (art. 57 of the Constitution). It is the autonomous-province clause, routinely left out, that gives Trentino-Alto Adige six senators: three for Trento and three for Bolzano. What the two chambers can do does not differ.
Source: Art. 70 of the Constitution
Two chambers of different size and identical power
The blocks are to scale: the Senate is half the Chamber. The band beneath them is single, because the powers are the same.
Here the two chambers differ
Chamber
400deputies
elected in constituencies
Senate
200elected senators
elected on a regional basis
This is what is called perfect bicameralism: the legislative function is exercised jointly by the two chambers, and neither can do anything in the band below on its own.
The Senate’s regional allocation has three floors fixed by the Constitution: at least three senators for each Region or autonomous Province, two for Molise, one for Valle d’Aosta. It is the autonomous-province clause, routinely left out, that gives Trentino-Alto Adige six senators: three for Trento and three for Bolzano.
What did the reduction to 400 and 200 change?
The number of members, not the powers of the chambers: deputies fell from 630 to 400 and elected senators from 315 to 200.
Constitutional law 1/2020 amended articles 56, 57 and 59 of the Constitution and has applied since the 2022 election. Overseas seats went from 12 to 8 in the Chamber and from 6 to 4 in the Senate, electoral districts became larger, and senators for life appointed by the President may never number more than five in office at once.
Source: Constitutional law 1/2020
What the 2020 reduction actually cut
Four cuts, all of about a third. Each row is scaled to its own starting number rather than to the other rows.
The outline is the number of seats before the reform; the solid bar is the number after. The rows are comparable because each is 100 against its own “before”: that is why 630 → 400 and 6 → 4 are the same shape.
beforefrom 2022
Deputies630 → 400−36.5%
Elected senators315 → 200−36.5%
Deputies for the overseas constituency12 → 8−33.3%
Senators for the overseas constituency6 → 4−33.3%
The powers of the two chambers
Unchanged. Constitutional law 1/2020 amended articles 56, 57 and 59 of the Constitution, which say how many members there are; it did not touch the articles that say what they do.
The reform has applied since the 2022 election. The cut made electoral districts larger — fewer seats spread over the same country — and brought with it an adjustment to both chambers’ rules on the minimum size of a parliamentary group.
Outside the drawing there is also the ceiling on senators for life appointed by the President, who may never number more than five in office: that is a maximum rather than a contingent, so it has no “before” to compare.
How long does a legislature last?
Five years, unless parliament is dissolved early.
The President of the Republic may dissolve both chambers, or just one of them, after consulting their presiding officers. Newly elected chambers meet for the first time within twenty days of the election.
Source: Art. 60 of the Constitution
What is a parliamentary group?
It is the body that brings together members of the same political persuasion, and it is the structure through which each chamber does its work.
Groups nominate committee members, share out speaking time and are received by the President of the Republic during consultations. In the Senate a group must have at least six senators and represent a party or movement that stood at the last election under its own symbol and elected at least one senator; anyone who joins no group ends up in the mixed group.
How many members does it take to form a group in the Chamber?
Fourteen deputies, from the twentieth legislature onwards — the one that will be elected in 2027.
It used to be twenty: the Chamber lowered the threshold in the amendments to its rules approved on 30 November 2022, which for this part apply from the following legislature. The minimum size of a political component within the mixed group was also cut from ten to seven. These are adjustments to the smaller Chamber, not a change in its powers.
Why can an elected member change group?
Because every member of parliament represents the Nation and exercises their functions without binding mandate.
Nothing obliges someone elected on a list to stay in the corresponding group: the seat belongs to the person, not the party, and the coalition declared before the vote does not bind the legislature either. The rulebooks have made new groups harder to create — they must correspond to a party that stood at the election — but moving to another group, or to the mixed group, remains possible.
Source: Art. 67 of the Constitution
Are there members of parliament who are not elected?
Yes, in the Senate: former Presidents of the Republic are senators for life by right, unless they decline.
The President may also appoint as senators for life citizens who have brought honour to the country through outstanding achievements in the social, scientific, artistic or literary field; appointed senators in office may never number more than five. They do not count towards the 200 elected seats, and they vote on confidence like everyone else.
Source: Art. 59 of the Constitution
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