CHENNAI: Chief Minister M K Stalin on Sunday asked the chief ministers of eight non-BJP ruled states to oppose the reference sought by President Droupadi Murmu before the Supreme Court.Stalin wrote a letter to the CMs of West Bengal, Kerala, Karnataka, Telangana, Himachal Pradesh, Jharkhand, Punjab, and Himachal Pradesh, asking them to put up a joint legal battle against the BJP govt at the centre for “preserving our federal structure and state autonomy.”“We must evolve a coordinated legal strategy before the Court and present a united front to preserve and protect the basic structure of the Constitution,” Stalin said in the letter.Citing the reference sought by the President, Stalin said, “The BJP is attempting to unsettle this judgement (on fixing the timeline for governors giving assent to bills), which can be invoked as a precedent by other states when faced with an obstinate governor. As the first limb of their ploy, the BJP govt has advised the President to seek a reference before the Supreme Court.”Recently, the President, under Article 143 of the Indian Constitution, invoked the advisory jurisdiction of the Supreme Court and raised 14 questions before the Apex Court.Raising doubts on the reference, Stalin said, “Its intent is to question the findings on law and interpretation of the Constitution given by the Supreme Court in the case of State of Tamil Nadu v. Governor of Tamil Nadu. This historic judgement obtained by my govt is not only for my state but for all states since it upholds the federal structure and distribution of powers between the states and the Union, thus effectively preventing the obstruction of legislations enacted by democratically elected state legislatures by an appointee of the union and an unelected figurehead – the governor.”