The DMK on Tuesday decided to boycott the state assembly sessions until the Tamil Nadu cabinet takes a policy decision to shut down the Sterlite Copper smelter plant in Thoothukudi belonging to the Vedanta group. In a statement issued by the party, Whip R. Chakrapani said the K. Palaniswami government issued an order closing down the copper smelter plant without convening a cabinet meeting and taking a policy decision. Chakrapani said this would enable the company to seek relief from the courts. He alleged that the Chief Minister was not sincere about shutting down the plant. The DMK lawmakers on Tuesday attended the Assembly wearing black shirts to condemn the May 22 police firing in Thoothukudi which claimed 13 lives.