Trade school for socialists and their comrades....
Certainly there can be an empirical study of justice and injustice, regardless of how tricky it might be to define "justice."
The problem, of course, is that we can't trust the "scholars" at ASU to define justice and "study" it in ways that will improve our understanding. Based on the rest of Horowitz's piece, it's fairly clear that this ASU program aims at political activism and radical social change rather than the objective empirical study of justice.