PARLIAMENTARY PRIVILEGES. - Traditionally, certain "prerogatives" (with consequent immunities) are recognized for parliamentarians (v. an example in the English bill of rights of 13 February 1688) in order to guarantee them independence in the exercise of their functions. This independence, moreover, in a state governed by the rule of law as modern democratic states generally are, and among them Italy, cannot be absolute and is therefore usually delimited by the constitutional charter itself; thus, for example, by Article 68 of the Italian one.
First of all, members of Parliament cannot be prosecuted for the opinions expressed and the votes cast in the exercise of their functions. And yet they are bound, in the formal modes of expression of that will (in the assembly, permanent or special committees, etc.), to the discipline laid down by the internal rules of the Chambers and to the application made of them by their respective presidencies. Moreover, they are not covered by immunity for anything that does not fall within the exercise of their functions, as, for example, for speeches made outside parliamentary proceedings (speeches, hypothetically insulting or defamatory, made in public or in private, and in private even within the parliamentary seat).
Deputies and senators may violate legal norms, and then they must be subjected to the appropriate sanctions; but if these are criminal sanctions, they enjoy a prerogative that formally pertains to the proceeding, and which nevertheless can affect the judgment in the sense that it may not be initiated. Without authorization of the Chamber to which he belongs, no member of Parliament may be subjected to criminal proceedings; nor may he be arrested, or otherwise deprived of personal liberty, or subjected to personal or domiciliary search, unless he is caught in the act of committing a crime for which a warrant or order of arrest is mandatory, according to the provisions laid down in this regard by the Code of Criminal Procedure. The competent judicial authority (public prosecutor), even before requesting authorization to proceed, may carry out any investigative act concerning the offense that does not impair the parliamentarian's liberty, and on the other hand the request for authorization cannot be omitted, not even if an arrest in flagrante has been carried out. Authorization must also be requested "in order to place under arrest or keep in detention a member of Parliament in execution of a sentence, even an irrevocable one"; it is not required, however (not being a sufficient ground), if the criminal judgment concludes with a sentence to a merely pecuniary penalty. The internal rules of the Senate and of the Chamber of Deputies govern the procedure for authorization.
From the abundant case law of parliamentary practice, no sure and precise rule seems to be derivable regarding the criteria for granting or denying authorization. As a matter of correctness, the tendency should as a rule be in the former direction (especially after a sentence of conviction, since otherwise a kind of right of pardon would be exercised, albeit with only suspensive or temporary effect), but if the act attributed to the parliamentarian has a political motive or coloring, the Chambers show themselves inclined to denial; in effect, full discretion of evaluation can lead in practice to recognizing immunities beyond those that would be in the spirit of the norm and ultimately to the discredit of the parliamentary institution. Once granted, authorization cannot be revoked; nor can it be waived by the individual interested parties, since the prerogative is directed, beyond and more than at them personally, at the protection of the legislative bodies themselves of which they are members.
The prerogative of forum no longer exists, which was held under the monarchy for senators, judged by the Senate itself, constituted as a High Court of Justice, a residual prerogative of a system of judgment by peers, which in a democratic regime no longer has any reason to exist and which has recently disappeared even in traditionalist England (Criminal Justice Act 1948, sect. 30, abolishing the special forum for members of the House of Lords).
The seats of the Chambers as well (Palazzo di Montecitorio for that of the deputies and Palazzo Madama for the Senate) enjoy a special immunity, which can be considered founded on a constitutional custom and is governed by the internal rules. Consequently, the powers necessary for the policing of the Senate and its seat belong (with respect to all those admitted there) to and are exercised by the president, assisted by the quaestors, who give the necessary orders to the guard on duty and arrange the appropriate measures with the competent authorities. The public force cannot enter the hall, except by order of the president (by a kind of so-called right of the house) and after the sitting has been suspended or adjourned. In case of outrage against the Senate or any of its members (who are to be considered public officials for criminal purposes) in the exercise of their functions, or of resistance to the president's orders, the latter may order the immediate arrest of the offender and his bringing before the competent authority. Analogous norms apply to the Chamber of Deputies and its members.