Time matters for competition law on a number of dimensions. Most obviously, the time in which new products or technologies are introduced (dynamic efficiency) is of course one of the key benefits of competition, alongside allocative and productive efficiency. Time is also important for the assessment of competition law. Think, for example, of the speed with which a market clears; the period within which we expect harm to competition or efficiencies to occur; the pace of supply side substitution; the non-transitory nature of a SSNIP or SSNDQ; the length of a profit sacrifice; the time in which potential or indeed responsive entry might occur; the period for paying off a sunk investment; or the benevolent nature of temporary market power as opposed to persistent market power. Time also introduces uncertainty into competition law, particularly when the assessment relates to future events, such as the likely impact of a notified merger on market conditions. The longer the time-horizon for merger assessments, the larger the degree of uncertainty. Such prospective assessments often imply the balancing of probabilities by decision-makers, which are subject to substantive, evidentiary and practical constraints.This paper focuses on the time that separates existing competition from potential competition, the uncertainty and risk that this time difference creates, and the extent to which the timeframe for a competitive effects analysis allows for an examination (and weighing) of existing and potential competition considerations
