The Italian Parliament is composed of the Chamber of Deputies (with 400 members or deputati elected on a national basis),[1] as well as the Senate of the Republic (with 200 members or senatori elected on a regional basis, plus a small number of senators for life or senatori a vita, either appointed by the President of the Republic or former Presidents themselves, ex officio).

Perfect bicameralism has been codified in its current form since the adoption of the Albertine Statute, and resurged after the overthrow of the fascist dictatorship of the 1920s and 1930s.

Following the 2020 Italian constitutional referendum, the number of MPs in the Parliament has been reduced from 630 to 400 in the Chamber of Deputies and from 315 to 200 in the Senate.

[8] No explicit age limit is required to be appointed senator for life (but Presidents of the Republic must be 50 or older).

The process by which the Italian Parliament makes ordinary laws, the iter legis ordinario, is as follows: Proposals can be made by the Government, individual Members of Parliament (who must present their proposal to the Chamber that they are a member of), private citizens (who must present a proposal in the form of a draft law, approved by 50,000 voters), individual Regional Councils, and the National Council for Economics and Labour (CNEL).

This procedure is obligatory for bills which concern constitutional and electoral matters, the delegation of legislative power, the authorisation of the ratification of international treaties, the approval of the budget.

If after the renewed debate the bill is approved by Parliament again, the President of the Republic is constitutionally required to promulgate it.

Once it has been promulgated, the law is published in the official gazette by the Ministry of Justice and enters into force after the vacatio legis (15 days unless otherwise specified).

In addition to its legislative functions, Parliament also reviews the actions of Government and provides it with political direction.

If the member who filed the injunction is not satisfied with the response, they can present a motion to hold a debate in the Parliament.

The provision of political direction embodies the relationship of trust which is meant to exist between Parliament and the Government.

Other means of providing political direction include motions, resolutions, and day-orders giving instruction to the Government.

In order to fulfill its function as the ordinary organ through which popular sovereignty is exercised, Parliament can employ the same investigative and coercive instruments as the judiciary in these inquests.

The Parliament meets and votes in joint session (Italian: Parlamento in seduta comune) for a set of functions explicitly established by the Constitution.

[23] The Chambers of the Italian Parliament enjoy special prerogatives to guarantee their autonomy with respect to other parts of Government: In some matters (e.g. employment disputes) the Italian Parliament acts as its own judicial authority (without using external courts), which is referred to as "autodichia" (self-judging).

137 of 2015 of the Italian Constitutional Court,[26] which agreed to rehear the appeal in the Lorenzoni case,[27] which had been dismissed the year before, it was stated that autodichia might be found in violation of the independence of the judiciary.

Article 68 lays down the principles of immunity (insindacabilità) and inviolability (inviolabilità), stating that "the members of parliament cannot be called to account for the opinions they express or the votes that they cast in the exercise of their functions" and that "without the permission of the chamber to which they belong, no member of parliament can be subjected to a body search or a search of their home, nor can they be arrested or otherwise stripped of their personal freedom, or imprisoned, except in the execution of a final court judgement or if caught in the act of a crime for which it is compulsory to arrest someone caught in the act.

Neither immunity nor inviolability are prerogatives of individual parliamentarians; they are intended to protect the free exercise of Parliament's functions against judicial interference, which occurred in earlier regimes when the judiciary was under Government control and was not autonomous.

The principle of inviolability results from Constitutional Law #3 of 1993, which revoked the earlier system of "authorisation to proceed" (autorizzazione a procedere) for convictions in cases with defined sentences.

The national elections for the renewal of members of the Senate of the Republic and Chamber of Deputies are regulated by Law n. 165 of 3 November 2017.

Notwithstanding this, a different threshold is needed for lists representing linguistic minorities, which is 20% and is calculated on a regional basis.