According to Geoffrey Robertson QC, human rights lawyer and adviser to Julian Assange, the British Supreme Court is likely to rule on his appeal against extradition this month. The personal consequences for Assange are grave, and unlikely to end in Sweden; the US has now arranged a secret grand jury indictment to deport him for trial in America – for crimes yet to be clarified but which, if proved, may see him imprisoned for many years.

Those who follow the case will know the sole issue is whether a Swedish prosecutor is a ‘judicial authority’ able to issue an arrest warrant under the Extradition Act. They may also know, through widely publicised remarks by his legal advisers, that English law sees this as an abuse of rights, contrary to ideals implicit in the separation of powers. The Supreme Court has granted an appeal because this issue has ‘great public importance’.

They are less likely to be aware the case raises a major issue of legal philosophy, posing a choice between competing theories of law, each with its idea of how legal principles operate. This theoretical issue will decide Assange’s fate because it will define the nature of his rights and how much protection they confer in a world where civilized nations resort to secrecy, rendition and torture in the name of national security and the public interest.

This jurisprudential issue went unseen by the High Court in Julian Assange v Swedish Prosecution Authority, which dismissed his earlier appeal in July, 2011, arguably due to the pervasive influence of a popular but controversial theory of law; it led the Court to interpret principles of justice governing his arrest by deferring to a Swedish practice which ignored them. This is a strong criticism, calling for careful examination of the judgment.

In a lengthy preamble to its decision, the High Court began by emphasising the role of principles protecting ‘fundamental’ rights, some with a history tracing back to Magna Carta.It emphasised the importance of these principles by citing from the Framework Decision, a pre-legislative treaty agreed to by Member States of the new extradition scheme, which said the aim of the scheme was to make it easier for justice to be administered across borders, at the same time protecting citizens’ rights, adding

‘That protection was buttressed by national courts remaining subject to rules protecting fundamental rights,particularly the ECHR and the Charter of Fundamental Rights of the European Union. The existence of the rights and the observance of those rights by the courts were intended to underpin a regime in which there would be mutual confidence.’

Although the Framework Decision is not mentioned in the British Act, the High Court explained that these principles and rights were ‘fundamental’, and its duty was to interpret the Act in light of this Framework treaty. It noted that the aim of mutual recognition was ‘subject to’ these constraints of justice.

Importantly, it did not see these principlesas a British invention- they were ‘principles universally accepted in Europe’ andapplicable to all Member States. Although it made no attempt to spell them out, it implicitly rejected any idea that they were national artefacts. Accordingly, member nations might have different laws and arrest practices, but this did not mean they were governed by different principles of justice; it meant that opinions as to what these principles require might vary, in which case courts must resolve the issue.

This is the same task an appellate court has when faced with conflicting interpretations of a constitutional principle by lesser courts in the same jurisdiction. It is important to make this point because media accounts of the trial see it as a conflict between different value systems – between British ideals of justice and Swedish principles which appear to ignore rights. This popular view adds drama to, but seriously confuses, the public debate.

However that may be, to dispel any doubts as to their authority the High Court explained that, if the Swedish Ministry of Justice were given power to issue warrants by Swedish law, this would be invalid, since it was ‘self-evidently’ not a judicial authority. This is, on its face, reassuring; it reminds us that not even a Minister of State, backed by democratic theory and the Swedish parliament, can ignore rights affirmed by all parties to the scheme.

But the judgment quickly reneged; it ruled that these basic rights would not disqualify a public prosecutor, with no greater interest in or duty torespect them than a justice ministry, and whose primary role was to bring criminals to justice, not defend them against unproven allegations. The Court did not say why it took this path, relying simply on an interpretation of ‘judicial’ broad enough to include prosecutors. It did so despite saying the statutory aim of mutual recognition was ‘subject to’ the principles which disqualify a Minister’s warrant.

In an earlier paper I said this contradiction was inherent in the Act, which imposed incompatible duties on judges; it asked them to recognize arrest practices of member nations while abiding by Framework principles which condemned them. This seems so obvious that a cynic might say the Act was drafted to avoid an invidious political decision – to rely on the judges, rather than politicians, to ignore rights everyone agrees are important. This, he might add, is why the Act itself made no attempt to clarify the matter.

Faced with this problem the High Court sought to resolve it by looking for an interpretation of ‘judicial authority’ able to accommodate Swedish practice and found it, not surprisingly, in Swedish practice, which gave powers of arrest to prosecutors, recognized their independence, and accepted them as members of judicial associations. It failed to see that, by citing national practice to interpret principles meant to govern it, it must negate the rights they protect.

How could such experienced judges fall into this tautological trap? The question invites a closer look at a theory of law, referred to above,which is widely influentialamong practitioners and judges. The theory, known as ‘legal positivism’, sees law in empirical terms as a model of rules which are the product of law-making bodies, primarily legislatures and courts. For a rule to be a rule of law there must be a judge or other authoritative person or body who, at a given time and place, made it so – be it to resolve a dispute or implement a legislative policy.

The theory says thatif there is no clear rule, or conflicting rules by courts with equal authority, judges have discretion to ‘make’ law to clarify the matter. Hence if a rule prohibits vehicles in the park, it excludes trucks, cars and motorbikes – probably ride-on lawn mowers and electric bicycles – but what about scooters, wheelchairs, pushcarts, hovercraft and model airplanes? In these ‘penumbral’ cases the theory insists that, because unclear law equates to no law, the court must decide what the law should be; it can now pursue a policy of its own, be it to deter noisy children or to encourage use of the park by the disabled.

The theory treats legal principles as less articulate rules which, being vaguer, confer more law-making power. Judges will be guided by previous interpretations but the spongy nature of principles is such that the central core of clear law may be small – the penumbra of unclear law large. It means judges interpreting principles will be making new rules, adding to the list of rules which collectively define their meaning. In doing so they exercise discretion akin to that of the legislature – they are free to pursue social goals of their choice – in Assange’s case either to support government policy by making extradition easier or to protect his rights.

This ‘realist’ view of principled decision-making is widely taken for granted by lawyers, political pundits and others, and has great influence on public debates; it underlies the main objection to a bill of rights, that it gives unelected judges immense power to legislate social policy. That complaint will remain as long as the positivist theory holds sway.

But this theory has grave flaws, as Ronald Dworkin, successor to the late HLA Hart in the Oxford Chair of Jurisprudence, explained nearly half-a-century ago. Law, he argued, cannot rest on a simple model of rules, and unclear law cannot be equated with a licence to make law. Legal principles, he reasoned, do not confer this kind of discretion; they are abstract but fully articulated standards, which impose a different kind of obligation on judges, but still govern the decision. They are, it might be said,designedfor unclear cases – their logic is adapted to this role in that, unlike rules, they have dimensions of both weight and point, which judges must judge. But if judges have this duty they are not free to pursue social goals – in Dworkin’s words, they are never off the hook of obligation.

Despite this account (the full thesis is in Law’s Empire, Fontana, 1986) which – after decades of argument and hundreds of books and articles – no one has yet managed to refute, the law-making theory has enduring appeal for lawyers. This is in part because it is seen as a ‘realist’ response to the more ambitious claims of classical Natural Law theory, its historical enemy, but also as a refutation of ‘mechanical jurisprudence’, a fictitious theoryof law invented to confirm its own superiority. Its continuing appeal isa testament to the value of Keyne’s warning about ‘practical’ men being the slaves of yesterday’s theory.

What influence, if any, did positivist thinking have on the Assange ruling, given the Act chose not to define the meaning of ‘judicial authority’, leaving this crucial law unclear? The theory says judges must do their best to fill the gap- they were free to support UK policy by dismissing the appeal, or protect Assange’s rights by allowing it. But this is where the theory comes unstuck because the idea that his rights should depend on such idiosyncratic factors as the policy preferences of judges is so repugnant to the judicial mind, and to the ideal of the rule of law, that it was never likely to be aconscious reason.

Instead the judges, aware their duty was to clarify rights not make social policy – a role for which they have neither mandate nor expertise – took the traditional path and sought to rest their decision on the ordinary, literal meaning of the Act, which they saw as an issue of fact; their ruling would then be impartial, because facts are not matters of choice.

The difficulty with this ‘objective’ approach was that the facts showed the meaning of ‘judicial authority’ in the UK was different to its meaning in Sweden so the decision, if one is a positivist, still required judicial choice. Assange’s fate was sealed when the Court opted for Swedish usage which, reflecting Swedish practice, furthered a policy of recognition – rather than a British common law meaning which protected his rights. So in the end the positivist theory prevailed. There is no hint of this anywhere in the judgment because the choice is never made explicit, and perhaps the judges themselves were not aware of it.

The second problem with this ‘objective’ approach is that the Court ignored its own advice that the Act must be read in light of the European Framework Decision and the basic rights and principles it espoused, including the European Convention on Human Rights and the Charter of Fundamental Rights of the European Union. If the Act must be read in light of these rights and principles, there is no room to choose a meaning for policy reasons.

If we now ask what this case has to do with legal philosophy, the answer seems clear: If judges could stand back from the theory which treats legal principles as fuzzier rules calling for judicial choice, they might see them as standards of a different kind, as precise in the duty they impose on courts as rules, and whose raison d’etre they have an obligation to interpret, just as they have a duty to assess their weight – they had, after all, more than enough weight to invalidate the arrest warrant of a Swedish minister.

Those interested in the rule of law as a moral and constitutional ideal will be anxious to see if Britain’s highest court can do a better job of defending it.