Rupert Haigh's book is an excellent starting point for intermediate or advanced users of legal English for whom English is a second language, and that is its intent. In fact, this is the only book I have identified that specializes in legal English for the ESL (English as a Second Language) environment. It is not a textbook, per se, but utilizes pedagogical approaches in effective ways. Haigh spends time on 'problem words' and good substitutes, the usual array of punctuation and grammar issues crossing culture and language, both. He includes very practical material on legal work tasks - with extensive material on, for example, letter writing, chairing a meeting, internal communications, telephone use, and making presentations. The final section of the book is devoted to contract language in English language contexts, and is the most excellent treatment of this that I have seen in print. He focuses on U.K. Legal English, making this book one of a kind. However, I found much of it useful and informative, from an international law standpoint - ie. despite it not being 'American' legal English.
As a teacher of legal English, I've used the extensive glossaries in his Appendixes most, perhaps - just great. Overall: Accessible and extremely informative.