Prime Minister Modi's "Dimagi Naxal" remark has triggered a fierce political confrontation, with the BJP calling it a warning against ideologies that undermine the Constitution and national unity, while the Opposition sees it as an attempt to stigmatise dissent. As P. Chidambaram embraces the label and the government insists it is targeting extremist thought, not political opponents, the bigger question remains: where does the line lie between protecting the nation and policing opinion?