This paper presents the findings of a corpus-based analysis of English modal verbs and semi-modals in modal verb phrase structures as well as lexical association of modality in ʼstandard terms and conditions of saleʼ, which are legally binding documents in the domain of commerce and whose purpose is to govern the obligations and rights of sellers and buyers in the transaction of goods for payment. Our research has established that the most frequent modal verbs in these documents are shall, will, may, must and can, and that the most common modal verb phrase structures in are ʼmodal+infinitiveʼ and ʼmodal+be+past participleʼ. We found 718 different lexical verbs that indicate actions, states and conditions associated with commercial transacti...