In this regard, it is very difficult to determine whether the threshold for objective justification is particularly high or whether, in the rare cases examined, the justification relied upon by the dominant undertakings has simply not been supported by facts. Vertical linking is the practice of requiring customers to purchase related products or services from the same company.  For example, a company could require that its cars be maintained only by its own dealers. To limit this situation, many jurisdictions require that guarantees not be invalidated by external maintenance; See z.B. Magnuson-Moss Warranty Act in the United States. The result of the lever also depends on the interaction between the requirements of the two products. The monopolization of the linked market could lead to lower sales and lower prices in the monopoly market if both products are completed and if the commitment results in the abandonment (or arrival) of more efficient producers of the good B.135 (or prevents the market). In addition, incentives for engagement would be stronger if consumer assessments were positively correlated for binding and related products. EU competition law uses almost the same loyalty analytical framework as U.S. antitrust policy. This does not mean, however, that the EC`s approach to the link is fundamentally identical to that of the United States. As U.S. cartel and abuse legislation has made clear, the same framework allows for a wide range of different strategies.
Within the same four analytical steps, U.S. policy has shifted from a position of hostility under the rule itself illegal, which does not recognize any legitimate objective of engagement, to a modified legal approach in itself, which at least implicitly accepted that the link between firms with market power could also increase efficiency. This journey is not over. Jefferson Parish continues to defend the general position on engagement, since the scope of Microsoft III has been limited by the Court of Appeal to the integration of products in the “platform software markets” and only then, legally, in the D.C circuit. However, the general direction of the trip has been clearly shown, and Microsoft III is unlikely to be the final step, since the Court of Appeal`s criticisms of Jefferson Parish are general and universal in nature. (2) Status of Competition in the Linked Market As we have seen above, anti-competitive link models assume that the linked market is imperfectly competitive;148, i.e. it is populated by companies facing positive fixed costs. Monopoly engagement costs its competitors on the cheap bound and reduces their revenues below the level required to cover their fixed costs.