This chapter explains the role played by reservations, the application of the rules of the Vienna Convention on the Law of Treaties, and practice in dealing with reservations. It defines reservations and distinguishes them from interpretative declarations and political declarations. It examines whether reservations are permissible or impermissible, including the test whether a reservation is incompatible with the object and purpose of the treaty. It also discusses the rules governing acceptance and objection, the legal effect of reservations, the question whether a prohibited reservation can be severed, and special cases such as human rights treaties, reservations relating to internal law, vague or general reservations, reference to Islamic law, late reservations, and the role of treaty monitoring bodies. It analyses the procedure for making or objecting to reservations or withdrawing them, and the functions of the depositary in relation to reservations.

Commercial contracts frequently contain mediation clauses requiring parties to mediate as part of a sequence of dispute resolution methods, where they progress from consensus to evaluative methods until resolution is reached. Careful drafting is required to ensure such clauses are effective and enforceable. The primary issues relevant to the enforceability of mediation clauses include severability, certainty, completeness, attempts to oust the court’s jurisdiction, additional policy considerations, certainty, waiver and remedies for breach of mediation clauses. While compliance with mediation clauses is not easy to determine, only the narrowest of requirements has proven workable in practice. Regional and international instruments covering mediation tend not to provide for the enforcement of mediation clauses. There is an international trend towards obligating legal advisors to discuss with their clients whether their commercial disputes are suitable for mediation, and policy in many jurisdictions is moving towards penalising parties where mediation is not given due consideration. Similar to mediation clauses, agreements to mediate require careful drafting to ensure enforceability.

Chapter 13 discusses numerous contractual clauses that are often relegated to the “back” of an agreement, but which can have important effects on the parties. These include the front matter of the agreement, definitions, assignment (PPG v. Guardian), marking, compliance with law, force majeure, merger and entire agreement, no waiver, severability, precedence, amendment, mutual negotiation, notices and interpretation.

The severability of the arbitration agreement, a cornerstone principle of international arbitration that is considered in the first chapter of this book, is more firmly established now than it was three decades ago. Yet respondents still from time to time call that principle into question by attempting to vitiate the arbitral process by invoking a (supposed) defect in the underlying contract or treaty, while difficult issues also remain concerning the precise scope and limits of the principle. These issues underscore the merit in analyzing and revisiting what remains a jurisprudentially subtle and practically important question.