In the name of Allah, the Merciful to all, the Compassionate
Article 50 of the Rome Statute allows any of the six UN languages (Arabic, Chinese, English, French, Russian and Spanish) to be used as a working language if the court case dictates. Currently, English is one of the two working languages of the United Nations (UN), the International Court of Justice, the International Criminal Court, and ad hoc UN-backed tribunals. At these courts and tribunals, documents and oral submissions may be presented in French or English and must be translated into the other language, at great expense. Although there are approximately 1.5 billion English speaking people, English itself has fundamental flaws that make it unsuitable to be the language of international law.
English has a vast collection of words for various objects and techniques, with an estimation of over one million words and definitions. That makes it relevant as a language of trade and technology. but when it comes to concepts, English has little to offer. For example this sentence has 7 different meanings depending on the stressed word: