According to historian Claudio Pavone[1] the arch was the informal heir to the National Liberation Committee, which had been established in 1943 to represent the anti-fascist parties that would go on to form the political leadership of post-war Italy.
The Action Party, which had a significant role in the resistance movement and contributed to the works of the Constituent Assembly, disbanded in 1947 and is thus not included in the definition.
While the Communist Party was effectively excluded from government posts and hypothetical coalitions until its dissolution in 1991 it nonetheless played an important role in policymaking through its participation in parliamentary committees and local administrations, while neo-fascists were consistently marginalised in political life.
One of the last overt expressions of the constitutional arch was the election of former partisan leader Sandro Pertini as President of the Republic in 1978, with the largest majority in a presidential vote in Italian history.
The arch finally ended in the early 1990s, with the collapse of all of its member parties and the decision of Silvio Berlusconi to found the Pole of Good Government, a coalition that included the Italian Social Movement and its post-fascist successors.