This may be the article I remember--the part towards the end caught my attention:

"The Dangerous Speech Project has gathered typical hallmarks of speech that seems to catalyze just such mass violence and has developed guidelines for analyzing the level of danger posed by a particular turn of phrase: how likely it is to lead to violence in a specific context. This analysis can be applied to any form of expression—a drawing, photograph, or film—not just words.

WHICH WORDS SPARK

One can estimate the likelihood that speech will spark violence in any given situation using just these five criteria: the speaker, the audience, the speech itself, the social and historical context, and the means of dissemination.

In each case, one or more of these criteria may be especially important. A speaker can have great influence over a particular audience, while certain audiences may be especially vulnerable, because of economic hardship, fear, or existing grievances. Certain language-related events—defined broadly to include such acts of expression as burning a book—can be particularly powerful. "

source: http://www.worldpolicy.org/journal/spring2012/words-weapons

There are more links at the bottom of this Berkman Center page: 
https://cyber.law.harvard.edu/events/luncheon/2014/03/benesch