Halliday (2008: 125-6):
Thanks to these two metafunctions, in the modern “globalised” world of corporate and state capitalism it is language that maintains and reinforces the political and economic power structures in which we live and move. Discourse analysts often refer to this phenomenon as “the language of power”. But there can only be a language of power because of the power of language; and the power of language depends, in turn, on the complementarity of system and text.