Question: Which son of Bernardo Mattarella was an elected judge on the Constitutional Court?
Related documents: [0]  [DOC] Sergio Mattarella, {'1': ", '2': ", '3': 'OMRI, OMCA', '4': "} (] ; born 23 July 1941) is an Italian politician, lawyer and judge who is the 12th and current President of Italy since 2015. He was a member of Parliament from 1983 to 2008, serving as Minister of Education from 1989 to 1990 and as Minister of Defence from 1999 to 2001. In 2011, he became an elected judge on the Constitutional Court. On 31 January 2015, he was elected by parliament to be the 12th President of the Italian Republic. He is the first Sicilian to have held the post. [END] 
[1]  [DOC] Bernardo Mattarella (15 September 1905 – 1 March 1971) was an Italian politician for the Christian Democrat party ("Democrazia Cristiana", DC). He has been Minister of Italy several times. He was the father of Piersanti Mattarella and Sergio Mattarella, who both became politicians as well; Sergio is the President of the Italian Republic since 3 February 2015 and Piersanti was President of the Regional Government of Sicily, before being assassinated in 1980 by "Cosa Nostra". [END] 
Answer: 
Sergio Mattarella
Sergio Mattarella