The binding legal principles established are: (1) Section 12 of the Competition Act establishes jurisdictional facts that determine whether a transaction constitutes a merger; once jurisdiction is established, the enquiry must proceed entirely under section 12A for substantive competitive assessment and should not revert to section 12 considerations; (2) In differentiated product markets, particularly dual-sided markets, market definition must be sensitive to the degree of product differentiation - differentiation in one side of the market (listeners) translates into differentiation in the other side (advertising); (3) Under section 55 of the Competition Act, the Tribunal may accept as evidence any relevant document whether or not it is given under oath or would be admissible in court, in keeping with the Tribunal's mandate to conduct hearings expeditiously and exercise inquisitorial jurisdiction; (4) On review of Tribunal decisions, courts must apply the principle of deference to the Tribunal's expertise in complex economic matters; the test is whether the Tribunal properly exercised its powers and whether the outcome is rationally justifiable, not whether the court would have reached the same conclusion; (5) MHHI assessments are designed to measure unilateral effects in homogeneous product markets and will grossly overstate merger effects in differentiated product markets, though they may serve as a crude starting point where better tools (like diversion flow analysis) are unavailable.