In Masstores (Pty) Ltd v Pick ’n Pay Retailers (Pty) Ltd 2017 (1) SA 613 (CC) the Constitutional Court found that the personal right of exclusive trade in the lease contract was contrary to public policy and not worthy of protection. To do so, the court relied on the ‘competition principle’ — that the competitor who delivers the best or fairest (most reasonable) performance must achieve victory, while the one rendering the weakest (worst) performance must suffer defeat. The court was of the view that, as a general proposition, third parties have no legal duty not to infringe contractually derived exclusive rights to trade. According to the majority, exclusive trading rights make the competitive field uneven. The court emphasised that the boni mores must be understood in terms of the values of the Constitution, and that the values contained in the Bill of Rights are a crucial tool in the development of the common law. Although the majority judgment focused on the delict of unlawful third-party interference in a contractual relationship and the nature of interdicts, the judgment relates also to the question of the personal right to commodus usus in a lease contract, and the remedies available to vindicate this right. The intersection of these issues is investigated in this note.