criteria provided by the constitution. With the exception of university professors, public servants (including members of the Armed Forces) are barred from running for parliament, unless they permanently resign their office before promulgation. Parliamentary groups Οnce MPs assume office, they form parliamentary groups. A parliamentary group in the Hellenic Parliament should consist of at least ten MPs who are members of the same party. Five MPs should also suffice provided the party they belong to had ballots in at least two thirds (2/3) of the constituencies and got at least three percent (3%) of the total number of valid ballots in the country. Provided they are an elected MP, a party leader presides over the respective parliamentary group. They may appoint up to two substitutes, though the president of the largest parliamentary group, the one which is actually in government, as well as the president of the major opposition party, may appoint up to three substitutes each. There are parliament premises meant for the exclusive use of parliamentary groups and independent MPs and parliamentary groups have their own administrative secretariats composed of revocable personnel. Surface area, number of offices, and the number of revocable staff working for parliamentary groups depend on their respective size and electoral strength. The president of the parliamentary group with the second highest proportion of MPs, i.e. head of the political party that is not in government, is referred to as the leader of the major opposition, and enjoys special prerogatives, such as extra time to speak before the assembly. Tenure Members of parliament are immune from criminal prosecution, arrest or detention while in office, with the exception of crimes committed in flagrante delicto. They are also immune from having to provide any information to any authority regarding their legislative functions and deliberations. However, both the constitution and the standing orders allow for the Public Prosecutor's Office to request the parliament to lift an MP's immunity for a particular crime, with MPs deciding through open balloting. Alleged crimes committed by members of the cabinet (including non-MPs) or the president of the republic are first investigated by an ad hoc parliamentary committee, with MPs then voting on the committee's recommendations. Should parliament determine that there is sufficient evidence for prosecution, an ad hoc special court is set up. Plenum The plenum is composed of all 300 MPs elected in the general elections, which are normally held every