A natural mechanism for eliciting rankings when jurors have favorites

•This paper analyzes the problem of a jury that must rank a set of contestants.•Jurors may have friends among the contestants and therefore, may be biased.•A necessary and sufficient condition for subgame perfect implementation is provided.•A natural mechanism that is solvable by backward induction is shown.

We analyze the problem of a jury that must rank a set of contestants whose socially optimal ranking is common knowledge among jurors who may have friends among the contestants and may, therefore, be biased in their friends' favor. We show a natural mechanism that is finite and complete informational, with no simultaneous moves (i.e., it is solvable by backward induction), which implements the socially optimal ranking with subgame perfect equilibria.