Methods of Interpretation

A method is a way of doing something.243 Methods of legal interpretation are ways of ascertaining laws. The use of some methods is legally required. It is on these methods, and on the legal norms that require their use, that I will focus in the following paragraphs.

It is important to distinguish the concept of (legally required) interpreta-tive methods from related concepts (infra, 5.1– 5.5). The notion of method is, indeed, used loosely and inconsistently in legal practice and scholarship. As a result, lawyers and legal scholars often talk at cross- purposes when they argue about interpretative reasoning. Thus, conceptual clarity is needed.

While they are often conflated in practice, legal norms that require the use of specific interpretative methods must be distinguished from normative in-terpretative theories (5.1), axiological and structural inin-terpretative principles (5.2), rules (5.3), auxiliary means (5.4), and argument types (5.5). I use the term

‘interpretative methods’ interchangeably with interpretative canons, maxims, guidelines, and principles (except for axiological or structural principles, infra, 5.2). A canon is an accepted normative principle.244 A maxim is a fundamental principle of conduct.245 Finally, a guideline is an indication or outline of policy or conduct.246

5.1 Normative Interpretative Theories

Legal norms that require the use of interpretative methods, eg textual or tele-ological interpretation, are not normative interpretative theories (or method-ologies) such as textualism or purposivism. Methods are conceptually distinct from what Olivier Corten calls ‘objectivist’ versus ‘voluntarist’ theories, which demand that laws be interpreted either separately from, or based on, the inten-tion of their authors.247 They are distinct from deontological versus utilitarian interpretative theories, which hinge on the moral philosophy the interpreter endorses. They also differ from what, in international law, is called ‘restrictive

243 As mentioned (supra, Chapter 1, section 7), a method is a ‘systematic procedure, tech-nique, or mode of inquiry employed by or proper to a particular discipline or art’, ie, a reasoned, ordered process. See <www.merriam- webster.com/ dictionary/ method>.

244 See the definition of ‘canon’ in <www.merriam- webster.com/ dictionary/ canon>.

245 <www.merriam- webster.com/ dictionary/ maxim>.

246 <www.merriam- webster.com/ dictionary/ guideline>.

247 Olivier Corten, ‘Les techniques reproduites aux articles 31 à 33 des Conventions de Vienne : approche objectiviste ou approche volontariste de l’interprétation ?’ (2011) 115 Revue générale de droit international public, Dossier : Les techniques interprétatives de la norme internationale 351.

interpretation’, a theory requiring that international law be interpreted so as to least interfere with a State’s sovereignty.248

Normative interpretative theories mandate giving priority to a specific as-pect of the interpretandum, such as its wording or drafting history, or so as to produce a particular result. They do not require that their users develop an elaborate normative framework: their endorsement is often implicit in judicial practice. Just like methods, normative interpretative theories exist in domestic and international law.249

Legal norms that prescribe the use of certain methods, by contrast, demand that decision- makers ascertain the law based on some features of the inter-pretandum. However, although there are categorical reasons for using these specific methods, interpretative norms do not typically provide categorical reasons for action.250 In other terms, norms requiring the use of specific meth-ods do not provide a meta- principle that directs how to choose among the dif-ferent directions in which various methods point. They merely mandate using some features of the interpretandum.

5.2 Structural and Axiological Interpretative Principles

Interpretative norms are a subcategory of legal principles. Principles are man-datory norms governing the interpretation of other legal acts, and are drafted at a relatively high level of generality and abstractness. A principle ‘states a reason which argues in one direction, but does not necessitate a particular de-cision’.251 While principles do not prescribe the outcome of a case, they orient and therefore constrain interpretative reasoning. Principles can be defeated by other, incompatible principles, provided there are good reasons for which these other principles must prevail.

248 On restrictive interpretation, see Luigi Crema, ‘Disappearance and New Sightings of Restrictive Interpretation(s)’ (2010) 21 European Journal of International Law 681;

Hersch Lauterpacht, ‘Restrictive Interpretation and the Principle of Effectiveness in the Interpretation of Treaties’ (1949) 26 British Yearbook of International Law 48; Rogoff (n 183) 607 ff. For a rejection of this theory, see icsid, Aguas del Tunari sa v. Bolivia, Decision on Respondent’s Objections to Jurisdiction, icsid Case No arb/ 02/ 3, 21 October 2005, at para 91.

249 Joost Pauwelyn and Manfred Elsig for instance note that international courts interpret treaties based on a ‘dominant hermeneutic’. See Joost Pauwelyn and Manfred Elsig,

‘The Politics of Treaty Interpretation: Variations and Explanations Across International Tribunals’ in Jeffrey L Dunoff and Mark A Pollack (eds), Interdisciplinary Perspectives on International Law and International Relations (Cambridge University Press 2013).

250 Eg Murphy (n 84) 32.

251 Ronald Dworkin, Taking Rights Seriously (Harvard University Press 1977) 26.

Norms prescribing the use of interpretative methods must be distinguished from another subcategory of principles, namely structural and axiological prin-ciples. These principles encapsulate a form of political organization or a value that judges must take into account when interpreting the law. In domestic law, such principles include the constitutional principles of proportionality, sub-sidiarity, and equality.252 In international law, structural and axiological princi-ples can (but need not) qualify as general principrinci-ples of international law. They include the principle of good faith, for instance, which is a general principle in the sense of art. 38(1)(d) icj Statute, and the principle of complementarity,253 which is not a general principle of international law.

Contrary to norms on interpretative methods, which point to features of the law that decision- makers must rely on, structural and axiological princi-ples provide criteria that interpreters must use when choosing among different possible interpretations.

5.3 Rules

In practice, norms prescribing the use of interpretative methods are often called ‘rules’. This is likely due to the fact that the use of methods is required by legal norms, which include rules.254 However, the two concepts are distinct.

Legal rules define what conduct is legally permissible. Once the facts have been established, legal rules can be applied to them in a syllogistic fashion.255 Although rules, like every legal act, are open- textured and can thus become vague in particular cases, they allow for deductive reasoning once they have been interpreted. Examples of interpretative rules include conflict rules (eg lex specialis or lex posterior) and rules of logic (eg a fortiori or ejusdem generis; on argument types, see infra, 5.5).256

252 Eg in Switzerland, the constitutional principle of the rule of law (art. 5 Cst.) or the consti-tutional principle of subsidiarity (art. 5a Cst.).

253 Art. 17 icc Statute.

254 Art. 31 vclt for instance is entitled ‘general rule of interpretation’. Contra Klabbers,

‘Virtuous Interpretation’ (n 93).

255 Hart and Sacks (n 155) 155.

256 Robert Kolb refers to such rules of logic as ‘arguments’ lawyers use for interpreta-tive purposes:  Robert Kolb, ‘Is There a Subject- Matter Ontology in Interpretation of International Legal Norms?’ in Mads Andenas and Eirik Bjorge (eds), A Farewell to Fragmentation: Reassertion and Convergence in International Law (Cambridge University Press 2015) 475. For a detailed analysis of a range of such rules (labelled ‘canons and principles’), see Joseph Klingler, Yuri Parkhomenko, and Constantinos Salonidis (eds), Between the Lines of the Vienna Convention? Canons and Other Principles of Interpretation in Public International Law (Kluwer Law International 2018).

Norms that prescribe the use of interpretative methods, by contrast, can sel-dom (if at all) be applied deductively. They are not ‘iron- clad rules’257 that de-termine the outcome of judicial interpretation. Instead, they point to relevant features of the interpretandum that decision- makers must take into account, and they require inductive reasoning (eg to determine the context or legisla-tive history of a legal act).

5.4 Auxiliary Means

Auxiliary means assist decision- makers in ascertaining the law. They are not sources of law, but material that helps interpreters in the identification of the law. In other words, auxiliary means are distinct from elements which (objec-tively) contribute to the formation and evolution of the law, even if they can influence these processes. One example of auxiliary means, under Swiss law, is ‘established doctrine and case law’,258 which Swiss judges must follow when filling gaps.

Norms that mandate the use of interpretative methods and auxiliary means are related. Auxiliary means may be necessary in order to use a given method. A judge may for example need to consult auxiliary means to identify the object and purpose or legislative history of a domestic statute or treaty.

Moreover, methods, like auxiliary means, assist interpreters in ascertaining the law. However, unlike methods, auxiliary means are not features of the law that judges must take into account when interpreting it. Instead, they help decision- makers in their interpretative task.

5.5 Argument Types

A last distinction concerns norms prescribing the use of interpretative meth-ods, versus what Scott Brewer calls argument types, ie, patterns of reasoning.

Scott Brewer lists four basic argument types: deduction, induction, analogy, and inference to the best explanation (or abduction).259

Scholars often refer to the inductive versus deductive method, and some have analyzed the practice of international law through the lens of such ar-gument types.260 The notion of method I refer to in this study is distinct from argument types, however. Indeed, a given method can be deployed through

257 ‘Article 19. Interpretation of Treaties’ (n 121) 947.

258 Art. 1(3) scc.

259 Brewer (n 213) 942 ff.

260 Eg Talmon (n 73). See also Anthea Roberts, ‘Traditional and Modern Approaches to Customary International Law:  A Reconciliation’ (2001) 95 American Journal of International Law 751.

various argument types. An argument type does not tell judicial decision- makers to which features of the law they must attend. Instead, it determines the logical structure their reasoning must adopt.