We study a voluntary contributions mechanism in which punishment may be allowed, depending on subjects' voted rules. We found that out of 160 group votes, even when groups had no prior experience with unrestricted punishment, no group ever voted to allow unrestricted punishment and no group ever...

Recent experiments have shown that voluntary punishment of free riders can increase contributions, mitigating the free-rider problem. But frequently punishers punish high contributors, creating “perverse†incentives which can undermine the benefits of voluntary punishment. In our...