From the late 1980s, due to industrialisation, and burgeoning vehicle population, air pollution in Delhi reached alarming proportions. The rising air pollution led to a protracted legal case, M.C. Metha vs. Union of India, filed by M.C. Mehta, an environmental activist lawyer. The case initially demanded the stoppage of stone crushing in the vicinity of Delhi. Even when interim judgments in the trial were made from 1986 onwards, by way of phasing out vehicles more than fifteen years old and the provision of hybrid fuels and bio-fuels, the state (both executive and legislature) did very little by way of policy or execution. It was only due to a sustained campaign by CSOs and threat of imprisonment for contempt of court by the judges that changes were eventually achieved. This case attempts to examine the way in which the Centre for Science and Environment (CSE) was able to generate, sustain, and coordinate public opinion with respect to vehicular air pollution as the main cause of public health problems, as well as playing an important role in convincing the public and judiciary that CNG (Compressed Natural Gas) constituted an ideal solution to the problem, especially in the face of strong opposing forces.