In this paper, I would like to reconsider rule incompatibility phenomenon, that is, the impossible application of two independent focus movements such as heavy NP shift and wh-movement in a sentence, from the viewpoint of new framework of Balance Theory. Through the discussion, it will be shown that the basic four types of rule incompatibility phenomenon can be explained naturally as a consequence of both End-Weight Principle and Top-Weight Principle. In order to assure the status of less acceptable cases, however, we have to appeal to the difference of the total weight between ungrammatical cases and subtle cases. In a sense, this phenomenon appears to be the most representative case to demonstrate the effect of the balance notion in the grammar of English.
