The Australian Competition and Consumer Commission (the Commission) has recently cited difficulties in proving that some mergers would result in a breach of Australian competition laws as part of a desire to explore whether Australia’s merger control regime needs reforming. For example, after a single judge of the Federal Court of Australia dismissed the Commission’s application in relation to Pacific National’s acquisition of Aurizon’s Acacia Ridge Terminal, ACCC Chairman Rod Sims made a number of statements on the need for merger reform: “I think we need a real rethink on how merger issues are dealt with in Australia… You’ve seen the Macquarie-AGL decision, you’ve seen this one – we have a problem”. The Commission has applied to the Full Court of the Federal Court for review of the judge’s decision. Our research into outcomes in contested effects (and purpose) cases do not provide support for over-hauling Australia’s merger control regime. At most, it could be that the processes for assessing mergers requires fine tuning but more experience for the recently enacted formal merger clearance process is needed before any decision is made.