This chapter examines the four main limits which are applied to the effectiveness of choice of court agreements. The first is the possible imposition of formality restrictions, such as a requirement that a choice of court agreement must be in writing to be effective. The second is a potential requirement for a dispute to have a cross-border element before a choice of court is permissible, ruling out a choice of a foreign court for purely domestic cases. The third is the possible overriding effect of exclusive subject matter jurisdictional rules, which recognise certain categories of disputes as so closely connected to a single legal order that the parties should not be free to choose a foreign court. The fourth is the potential existence of special jurisdictional regimes dealing with weaker contracting parties such as consumers and employees, under which those parties may be protected from disadvantageous jurisdiction agreements. The analysis of each of these potential restrictions highlights that the means for recognising these concerns, or indeed whether they are recognised at all, is significantly varied in the different legal systems under examination.