[1] Before World War II (1939–45) Bonnefous was involved in political economy and foreign policy, and made various trips abroad for study purposes.

[1] Bonnefous was a candidate for election to the National Constituent Assembly on 21 October 1945 on the "Republican Concentration" platform, but did poorly.

After this he was one of the founders of the Rally of Left Republicans (Rassemblement des gauches républicaines, RGR), and was elected Deputy for Seine-et-Oise on this platform on 10 November 1946.

He wrote, "France fortunately shows more distrust towards the vanquished, even towards the repentant ones, then its allies, believing that caution is a more important consideration than the desire for a democratic reeducation of Germany.

[3] He was the main author of a 19 March 1948 motion calling for the government to "work for the early convening of a European Constituent Assembly".

[3] In the opening session of the Council of Europe in August 1949 Bonnefous called for the European countries to "agree to pool their natural resources under a joint international administration.

"[6] He also warned, "if the German revival is not integrated in the economic organization of Europe, it will be carried out against the other European countries.

[3] He was opposed to the European Defence Community proposed in 1950 by René Pleven, the French Prime Minister.

The European Community is in this case in danger of appearing to be not a permanent necessity, but an ephemeral and provisional creation.

This ran into resistance from Britain and the Scandinavian countries, and a much less ambititious European Transport Office was eventually proposed.

[1] On 9 July 1955 Bonnefous gave an outline to the Consultative Assembly of the Council of Europe of the plan for a European Posts and Telecommunications organization.

[11] The plan covered exchange of information, simplification of cross-border postal arrangements, technical cooperation, European television, stamps with a common figure of Europe and shared investments.

[12] Bonnefous argued at the Quai d'Orsay and then at the Council of Europe that the scope should include the Organisation for European Economic Co-operation, Finland, Spain and Yugoslavia.

The subcommittee rejected the larger membership on the grounds that it would infringe on the authority of the national governments,[14] On 20 January 1956 the PTT ministers of the six members of the ECSC met in Paris to discuss the common arrangements.

[16] Bonnefous was reelected to the Chamber of Deputies on 2 January 1956 on the RGR platform, and on 2 February was again elected president of the UDSR parliamentary group.

He continued to head the management committee of L'année politique, and gave courses on Economic Geography at the Institut des hautes études internationales.

He moved toward opposition to Gaullism, criticizing de Gaulle for lack of commitment to the European Union and excessive distrust of the United States.