Political parties in Tamil Nadu are moving the Supreme Court against the Special Intensive Revision of electoral rolls in the state ahead of next year’s Assembly elections. Ever since the Election Commission announced a nationwide rollout of SIR last week, non-BJP ruled states — including Tamil Nadu, Kerala, and West Bengal — have raised strong objections. They allege that the move poses a threat to the democratic process and could lead to large-scale voter disenfranchisement. So what exactly is the issue with SIR, and why are these states opposing it?