New Delhi, April 22 -- The Supreme Court on Tuesday sought the response of the Centre on a petition challenging the validity of the National Investigation Agency (NIA) Act for violating the federal structure and Centre-state distribution of powers under the Constitution. The court was hearing a public interest litigation (PIL) filed by a Kerala-based lawyer Mohammed Mubarak Ali who is also an accused in a case probed by NIA into alleged unlawful activities of the banned outfit Popular Front of India (PFI). The petition questioned the arbitrary nature of the provisions contained in the 2008 Act which allows NIA to take over any case already probed by the state police under section 8 which allows NIA to take over a case "connected" with any s...