This study develops a new method of discourse analysis using speech act theory and formal ontology. The method constitutes an attempt to make discourse analysis more formal and repeatable. The study applies the method to a corpus of bi-lingual, interpreted legal dialogue, focusing on the speech act of clarification and its component acts. While discourse analysis is primarily a qualitative tool, it can be applied quantitatively by counting certain types of discourse, such as clarification speech acts. Dialogues are still analysed, utterances are classified as speech acts and their semantic relationships are qualitatively assessed. Subjectivity of human analysis is minimised using a new method of discourse analysis that employs a formal ontology. The ontology is stated in higher-order logic making the annotation of the corpus more objective, formal and repeatable than prior research. Keywords: Hong Kong, interprétation judiciaire, ontologie, corpus, Hong Kong, ontology, court interpreting, corpus