Following the flood of 4November 1966 when Venice, Chioggia and the other built-up areas in the lagoon were submerged by a tide of , the first Special Law for Venice declared the problem of safeguarding the city to be of "priority national interest". This marked the beginning of a long legislative and technical process to guarantee Venice and the lagoon an effective sea defence system.
To this end, in 1975 the State Ministry of Public Works issued a competitive tender, but the process ended without a project being chosen from those presented as no hypothesis for action satisfied all the mandated requirements. The Ministry subsequently acquired documents presented during the call for tender and passed them to a group of experts commissioned to draw up a project to preserve the hydraulic balance of the lagoon and protect Venice from floods (the "Progettone" of 1981).
A few years later, a further Special Law (Law no. 798/1984) emphasised the need for a unified approach to safeguarding measures, set up a committee for policy, coordination and control of these activities (the "Comitatone", chaired by the President of the Council of Ministers and consisting of representatives of the competent national and local authorities and institutions) and entrusted design and implementation to a single body, the Consorzio Venezia Nuova, recognising its ability to manage the safeguarding activities as a whole.
The Venice Water Authority – Consorzio Venezia Nuova presented a complex system of interventions to safeguard Venice (the REA "Riequilibrio E Ambiente", "Rebalancing and the Environment" Project), which included mobile barriers at the inlets to regulate tides in the lagoon. In this context, between 1988 and 1992, experiments were carried out on a prototype gate (MOdulo Sperimentale Elettromeccanico, hence the name MOSE) and in 1989, a conceptual design for the mobile barriers was drawn up. This was completed in 1992 and subsequently approved by the Higher Council of Public Works then subjected to an Environmental Impact Assessment procedure and further developed as requested by the Comitatone. In 2002 the final design was presented and on 3April 2003, the Comitatone gave the go-ahead for its implementation. The same year, construction sites opened at the three lagoon inlets of Lido, Malamocco and Chioggia.