LAHORE- Supreme Court’s Justice Jawwad S. Khawaja today said that ethnicity was the cause of social and class contradictions. Addressing a conference on water and environmental justice at Punjab Judicial Academy, Justice Jawwad S. Khawaja said that the constitution demands national language Urdu should be used in the routine life. Stressing on practicing the constitution in letter and spirit, he said that conversing in Urdu was imperative for eliminating the class contradiction. Justice Jawwad S. Khawaja said that the people should be made aware of the use and conservation of water. He said that the future generation would suffer most if the water reserves were not valued, harnessed and used judiciously.