A referendum on the voting system was held in San Marino on 3 August 2003.^[1] The proposed change would have reduced the number of preferential votes from three to one.^[1] Although it was approved by 80.72% of voters, the number voting in favour (8,755) did not pass the required quorum of 32% of all registered voters (10,105).^[1]

The original proposal was to only reduce the number of preferential votes for overseas voters.^[1] However, the Electoral Tribunal ruled on 10 June 2003, that this was inadmissible, as it differentiated between voters in the country and abroad.^[1]