A group of experts has to pick one winner from a group of candidates. Each expert has a judgment about who is the best candidate. A social choice rule (SCR) is a function that aggregates experts’ judgments to determine the deserving winner. Experts may be biased and not want to reveal their judgments. We state a necessary and sufficient condition for implementing an SCR in dominant strategies. We show that no -supermajoritarian SCR with or -submajoritarian SCR with satisfies this condition
