This paper investigates the language of legitimation considering a number of open letters
published by the pressure group Scientist Rebellion (SR) to address sustainability issues. The
questions this paper seeks to address include the following: Which legitimation strategies did
the authors of the open letters examined make use of to buttress their arguments? Did these
resources serve a legitimatory function, a delegitimising function against adversaries, or both?
Are the open letters under investigation characterized by legitimising mechanisms that are
specific to this genre? Using van Leeuwen‟s theoretical framework, a number of legitimation
strategies are identified, which were put in place by SR representatives to raise awareness of
questions concerning sustainable development (SD) and to seek public consent in relation to
their proposals.