The phrase 'โดยที่ (dooy thîi)' in Thai language is used to express the method, means, person or way by which an action is carried out. Usually used to begin a clause that explains how something is done or by whom it is done, it adds an extra layer of information to the sentence, providing details or clarifying a point. The structure can be used with various sentence structures, and can roughly be translated to 'by which', 'by whom', or 'whereby' in English. It is also used in legal documents to define the terms of a contract or regulation.