It is not just because we are an enlightened and open-minded people. It turns out that it is in the UK’s best interests to be a strong advocate of binding international rules. We are a country particularly exposed to risks in the world, with the largest financial center in the world, significant trade flows and citizens who love to travel a lot. More than most countries, we need to know that laws are obeyed and debts are paid. Over the centuries we have become so renowned for our reliability and expertise that people all over the world want to settle their disputes under English law. Such preeminence has increased our influence and our soft power even as our physical power in the world has diminished.
Yet the concept of international law also has, for Britain, far beyond even this daily importance. It has provided the foundation and rationale for some of our most important decisions as a nation. The 1914 declaration of war was aimed specifically at confirming a conventional commitment to Belgian neutrality, unlike Germany’s decision to view this as “a piece of paper.” The establishment of the Nuremberg trials in 1945 was, in the words of the prosecution, “to use international law to face the greatest threat of our time – the war of aggression.”
Successive prime ministers have justified their actions abroad on this basis. In 1982, Margaret Thatcher cited “international law must be respected” as one of the three guiding principles of her position on the Falklands. When Russia committed the Salisbury poisonings on our soil two years ago, Theresa May sought and received support from other countries on the grounds that it was “the role of the Russian state in the development of chemical weapons, contrary to international law. “. It is on a similar basis that the UK today opposes acts of aggression, such as Assad’s use of chemical weapons, or treaty violations, as evidenced by recent actions by China in Hong Kong.