The legal-administrative principle that establishes that administrative activity for fulfilling people's needs whether ensured by parties (local public bodies, in this case it is called vertical subsidiarity) or the citizens themselves, either individually or in associations or volunteer groups, (in this case it is horizontal subsidiarity) must be ensured by the party closest to the citizens (the concept of proximity, on both a decisional and implementation level). These functions may be exercised by higher levels of local administration only when these can deliver the services more effectively and efficiently. Action by parties on a higher level must however be temporary and aim to restore autonomy of action to the lower-level body in the shortest time possible. The principle of subsidiarity has been incorporated into Italian law with article 118 of the Constitution, as amended by Constitutional Law no. 3/2001