Lucius Caflisch has become the first Swiss expert to be appointed to the Geneva-based United Nations International Law Commission.
The foreign ministry said it was very pleased with Caflisch's election to an international body highly valued for its work in defining legal standards.
Switzerland considers international law an important part of its foreign policy, a statement said.
Caflisch is professor at the Institute of International Studies at Geneva University. He was also director of the institute between 1984 and 1990.
The 69-year-old law expert represented Switzerland at several international conventions, for example on banning personnel mines and on maritime law, and at negotiations creating the constitution of the international criminal court.
He also acted as judge for the principality of Liechtenstein at the European Court of Human Rights between 1998 and 2006.
The International Law Commission consists of 34 independent members elected by the UN General Assembly for a five-year mandate.
The committee meets twice a year for five-weeks at a time in Geneva, the UN's European headquarters.
Other Swiss experts
Caflisch is one of three Swiss legal experts nominated to a high-profile position within the UN. In 2004 Nicolas Michel was named head of legal services, while Walter Kälin became the secretary-general's representative on internally displaced persons in the same year.
Caflisch's appointment comes after two other Swiss experts failed to be elected to UN organisations earlier this month.
The head of the government's development agency, Walter Fust, lost out against a candidate from the United States for the position of director of the UN's World Food Programme.
And Marc Furrer withdrew his candidature for head of the International Telecommunications Union after coming last among the six candidates in the second round of voting.
swissinfo with agencies
Switzerland is the 12th biggest donor to the UN.
Around 120 Swiss citizens work for the 120 international organisations - 1.8% of the total staff.
Switzerland became a full member of the UN in 2002 but was active in UN organisations prior to that.
25 international organisations have their headquarters in Switzerland, mainly in Geneva, but also in Basel and the capital, Bern. Swiss citizens are underrepresented in most of these institutions.
Switzerland's best-known representatives include Adolf Ogi (UN Special Advisor on Sport for Development and Peace), Jean Ziegler (UN Special Rapporteur on the Right to Food), Carla Del Ponte (chief prosecutor of the War Crimes Tribunal for the Former Yugoslavia) and Nicolas Michel (head of UN legal services).
Two other Swiss recently failed in their bids to be elected to high-profile posts in international organisations: Walter Fust (UN World Food Programme) and Marc Furrer (head of ITU).