Thorn was born inLuxembourg City. His early childhood, however, was spent in Strasbourg, where his father worked for the French railways.[2] At the outbreak of World War II the family returned to Luxembourg.[2] While still at school he engaged in resistance activities during theGerman occupation, and spent several months in prison. After the war, he initially studied medicine inMontpellier, then switched to law, and continued his studies inLausanne and Paris,[2] and practised law in Luxembourg from 1955.[3] In 1957, he married Liliane Petit, a journalist.[2] He entered politics in 1959, representing the liberalDemocratic Party. He was a member of theEuropean Parliament from 1959 to 1969.[1] He was Chairman of the Democratic Party from 1962 to 1969.[4] From 1961 to 1963, he was one of the aldermen of the City of Luxembourg.[3]
Thorn was Foreign Minister and Foreign Trade Minister of Luxembourg from 1969 to 1980,Prime Minister from 1974 to 1979 and Minister of Economics from 1977 to 1980. He was alsoPresident of the United Nations General Assembly from 1975 to 1976 for its 30th session.[3]
As Prime Minister from 1974 to 1979, he presided over a socialist-liberal coalition between his own Democratic Party and theLuxembourg Socialist Workers' Party. This was the first Luxembourg government since World War II that did not involve the dominantChristian Social People's Party (CSV), and similarly, he was the first non-CSV prime minister since the war. He was the head of government even though his party had fewer seats in the legislature than its coalition partner.
Thorn (second from the left) at the 1983 G7 summit
In 1980, Thorn was chosen as president of the commission of the European Communities (now called the European Union), in succession toRoy Jenkins. He took office on 12 January 1981. France and Britain had been against his appointment as commission president, whereas his candidature was supported by the smaller countries and by West Germany because of Luxembourg's involvement in building up the commission.[1]
His presidency was marked by several difficulties. It coincided with a time of economic and political crisis, ofEurosclerosis, inside the European Community.[1] Relations between the commission and British government underMargaret Thatcher declined, over her demands that Britain should be compensated by other countries for its share of payments towards the commission budget.[1] There was also tension due to other EC governments' reservations about Britain's role in theFalklands War; and due to some European leaders' opposition to United States foreign policy and the deployment of cruise missiles and Pershing missiles in Europe.[1] This was in addition to the long-running international recession and occasional threats of trade wars. This all "combined to put the aspirations of Thorn and other supporters of European integration on hold".[1] However, as EC President, Thorn did manage to reach agreement on a common fisheries policy, and laid the basis for Portugal and Spain joining the European Community. Greece had just joined when his mandate started in 1981.[1]
Although Thorn was not considered a very forceful commission president, during his term of office, the commission continued to expand its power, both at the expense of the national governments of EC members and of the European Parliament, with which it engaged in a constant power struggle. In this, Thorn laid the groundwork for his successorJacques Delors, who took the commission to the height of its power.
After leaving the commission presidency in 1985, Thorn went into business. He was chairman of Luxembourg's largest media companyCLT,[1] and president of theBanque Internationale à Luxembourg from 1985 to 1999.[3]
Thorn remained active in international and political affairs, as President of theInternational European Movement and as a member of theTrilateral Commission, the Bilderberg conference[1] and of theJean Monnet Committee. He was also president of theLiberal International. He was married to Liliane Thorn-Petit (1933–2008), a journalist, with whom he had one son.[2]