I'm familiar with Letting go of the Words and www.plainlanguage.gov, and I have seen Sandra Fisher-Martins' Ted Talk, but I was wondering if there were any other sources, particularly academic sources, that talk about plain language, especially ones with a social justice bend.
I've found the following peer-reviewed academic journals on the Plain Language topic that you can check out:
The Case for Plain Language By: Douglas, Kristin Vickers; Smith, Becky; Parker, Beverly; Mehr, Holly; Ruud, Kari; Hathaway, Julie; Behrenbeck, Julia; O'Brien, Michael; Smith, Steven; Patient Education Management, 2011 Jul: Supplement: 1-4. (journal article) ISSN: 1087-0296
Introducing Plain Language Principles to Business Communication Students By: Greer, Rachelle R. Business Communication Quarterly. Jun2012, Vol. 75 Issue 2, p136-152.
Can the Law Speak Directly to its Subjects? The Limitation of Plain Language By: Assy, Rabeea. Journal of Law & Society. Sep2011, Vol. 38 Issue 3, p376-404. 29p.
AND THE WINNER IS: HOW PRINCIPLES OF COGNITIVE SCIENCE RESOLVE THE PLAIN LANGUAGE DEBATE By: Baker, Julie A.. UMKC Law Review , Winter2011, Vol. 80 Issue 2, p287-305, 19p
PLAIN LANGUAGE LEGISLATION: A COMPARISON OF APPROACHES By: Leete, Burt A. American Business Law Journal. Winter81, Vol. 18 Issue 4, p511. 14p.
Plain English Laws: Symbolic or Real? By: Timm, Paul R.; Oswald, Daniel. Journal of Business Communication. Spring85, Vol. 22 Issue 2, p31-38. 8p.
And this UX oriented article by Janelle Estes: User-centric vs. Maker-centric Language: 3 Essential Guidelines