1. FIRST SCREEN: IS AN ANTI-COMPETITIVE EFFECT POSSIBLE? The first screen is whether it is possible that the practice of coupling in question could have anti-competitive effects.144 The models described in Section V.B, a series of conditions necessary to link anti-competitive effects. However, a link that meets these conditions does not necessarily have anti-competitive effects. Other conditions need to be verified – these additional tests are part of the second screen.145 Modem Economic Thinking largely supports the adoption of the rule of reason approach for the analysis of link cases adopted by the D.C Court of Appeals regarding the software in Microsoft III. Economic literature shows that attachment generally has benefits for consumers or reduces production costs. The same literature also shows that attachment has anti-competitive effects that occur in particular circumstances; These circumstances have been identified as specific cases of models based on stylized assumptions.117 In the following paragraphs, we will examine the history of the economic contributions that led to this consensus. (a) Per-per-law inherently inappropriate in Microsoft III The Court of Appeal referred to the decision of the Supreme Court of Broadcast Music, v. CBS,57, which warned that “it is only after considerable experience with certain commercial relationships that the courts classify them as offences per se.” 58 According to the Tribunal, the vast majority of related cases dealt with by the Supreme Court concerned either the packaging of the sale or the leasing of a potential product when purchasing certain unpatented products (such as IBM/USA) or contractual ties (such as Northern Pacific Railway/U.S.). 59 The tether is generally beneficial to consumers because it allows businesses to reduce costs and better meet consumer demand. Given that it is often pro-competition, the department agrees with the vast majority of commentators that the link should not be valued under a rule of clandestineity.
United States v. Microsoft was another important case of engagement.  For some accounts, Microsoft connects Microsoft Windows, Internet Explorer, Windows Media Player, Outlook Express and Microsoft Office.