A bench of Justices Jagdish Singh Khehar and Adarsh Kumar Goel also issued notices to the firm and the Centre on Pillai's plea in which she has also challenged the validity section 499 (defamation) of the IPC.
The activist has contested the defamation complaint on the ground that Essar has filed it to curb the freedom of expression and prevent her from raising voice against the alleged wrongs of the company.
Earlier, another bench, hearing a batch of petitions challenging penal laws on defamation including the plea filed by BJP leader Subramanian Swamy, had allowed Pillai's counsel to argue her plea.
The criminal defamation suit was filed in a lower court of Madhya Pradesh against Pillai and two other persons related to Greenpeace -- Kumi Naidoo and Samit Aich.