Because no country can interfere in another’s legal system, there is little the UK can do to help the six Britons jailed in India for possessing ‘illegal’ firearms which were, in fact, fully authorised for the protection of shipping against piracy. Where David Cameron failed, Boris might try an appeal based on ius gentium, ‘the law of nations’.
Cicero was the first Roman to discuss the idea. He talked of societas (‘the state of association between people’) having the ‘widest possible application, uniting every man with every other man’. The jurist Gaius (c. AD 150) put it in legal terms like this: ‘Every people governed by statutes and customs observes partly its own peculiar law and partly law common to all mankind. The former… is called ius civile as being the special law of that state (civitas); but the law which ‘natural reason’ establishes among all mankind is observed equally by every people and is called ius gentium as being the law applied by all nations.’ The former is right because it is the law; the latter is the law because it is right.
This law of ‘natural reason’ was called ius naturale. For Cicero, ius naturale derived from divine reason i.e. the principle of ‘order’ which governed the physical world and gave man his own power of reasoning. It therefore explained the source of ius gentium and made the two ‘laws’ effectively identical. But Romans never developed this idea to embrace the notion of a higher law which could override state law, though Sophocles, for example, had partly based his tragedy Antigone on the clash between the two. Romans never attempted to make the idea of ius gentium internationally justiciable.
Had they done so, they might have returned to Quintus Scaevola’s formula, quoted by Cicero, of the importance of transactions being governed ex fide bona, ‘in good faith’. In India, a country whose legal system is riddled with corruption, a little fides bona would go a very long way.