A pioneer of the Union and a steadfast federalist, Altiero Spinelli was one of the authors of the Ventotene Manifesto, one of the first documents to embrace the idea of creating a united Europe and a European constitution. Along with other political prisoners, he drafted the manifesto while imprisoned by the Italian fascist regime on the island of Ventotene.
After World War II, Spinelli founded the European Federalist Movement in Italy. Throughout the 1940s and 1950s, he was a fervent advocate for a federal united Europe. In the 1960s, Spinelli, as a government advisor and researcher, established the Institute for International Affairs in Rome. He was a member of the European Commission from 1970 to 1976, and in 1979 he was elected as a member of the European Parliament.
In 1980, together with other like-minded members of the European Parliament, he founded the Crocodile Club, whose members submitted a proposal to Parliament to draft a proposal for a new treaty for the European Union. On February 14, 1984, the European Parliament overwhelmingly approved his proposal and adopted the “Draft Treaty Establishing the European Union”, the “Spinelli Plan”.