The company and its CEO, Mark Caruso, are also suing Cape Town attorney Cormac Cullinan, Amadiba Crisis Committee activist Mzamo Dlamini and social worker John Clarke for defamation in relation to comments they made about the company's involvement in a separate project.
Centre for Environmental Rights executive Melissa Fourie said the suit against her lawyers and the activist was "strategic litigation against public participation" intended to censor, intimidate and silence critics by burdening them with "the management and costs of a legal defence until they abandon their criticism or opposition".
She said the suit was also aimed at sending a message to activists that they opposed the company at their own risk.
The Centre for Applied Legal Studies asked to be admitted as friend of the court to present evidence on the nature and effect of this type of suiton academic freedom.
In its application, the centre's Lisa Chamberlain said this type of suit "had the effect of closing down space for public participation as it discouraged free expression and public participation by making it costly".
She argued that academic comment should generally be respected and guarded.
"To not do so would have a self-censoring effect on academics which would limit the pushing of boundaries in the fields of study in which they are engaged and force them to limit themselves in the interrogation of case studies for fear of lawsuits," she wrote.
The University of Cape Town has also applied to be admitted as friend of the court.
The defamation case is expected to be heard next year.