Pincas (p. 40, 2001) discusses the problems of using English as an international language for education, arguing it is "impossible to define 'Standard English'". However, there are controlled natural languages, most notably the "ASD Simplified Technical English" (ASD-STE100, aka STE) for aerospace manuals (Kuhn, 2014). STE provides a simplified grammar and style rules, as well as a limited dictionary. It clearly is possible to define a standard English for use in a discipline, should the discipline wish to devote resources to the task.
Kuhn, T. (2014). A survey and classification of controlled natural languages. Computational Linguistics, 40(1), 121-170. Retrieved from http://www.mitpressjournals.org/doi/full/10.1162/COLI_a_00168#.VsV7nUKfFyQ
Pincas, A. (2001). Culture, cognition and communication in global education. Distance Education, 22(1), 30-51. Retrieved from http://www.tandfonline.com/doi/pdf/10.1080/0158791010220103