In its recent ruling in the Uniplex case (C-406/08), the European Court of Justice (ECJ) criticised the way the UK courts apply the time-limit for bringing proceedings for breach of procurement law. Under national law a case must be brought “promptly or in any event within three months”. The issue which the ECJ was asked by the national court to consider was how the rule should be applied and the degree of discretion which the national court has to extend the limitation period. To date, the national courts have considered that time begins to run when the breach occurs. The ECJ however takes the view that the time for bringing proceedings can only begin to run from the date on which the claimant actually knew, or ought to have known, of that infringement. In the facts of the Uniplex case, time began to run not when the bidder was informed it was rejected but only at the point when it was given the reasons for its rejection and could take an informed view. The ECJ also added that a national rule which allows courts to dismiss proceedings for not being brought ‘promptly’ even when proceedings are commenced within the three month time limit is inconsistent with the principle of legal certainty. The ECJ took the same view in relation to a similar provision in Irish law in a parallel Judgment (C-456/08). The rulings, to some extent, lower the bar for an adversely affected bidder to take action in the UK and Ireland. Dissatisfied bidders will nevertheless be well advised to act quickly if they want to make a challenge. For their part, contracting authorities will have an incentive to be open and clear about decisions in order to demonstrate that bidders knew, or at least ought to have known, about any issues over which they have concerns.