En-masse cancellation impermissible where individualized review can distinguish tainted from innocent; proportionality and procedural fairness required. En-masse cancellation is permissible only where wrongdoing so pervades the process that innocent cannot be separated from tainted; otherwise each selection by different bodies must be examined individually. Procedural fairness mandates specific pleading of disqualifications and opportunity to meet allegations; representative impleading and public notice are required when private parties are treated as class representatives. Wholesale annulment without targeted examination may violate principles of natural justice and proportionality and be arbitrary when infirmities affect identifiable subsets.