an authority, despite his lacking the power, acts on an issue; in either instance, the ultra vires principle applies. Then, only a Constitutional Court can decide that dispute. He also submits that if the proceedings impugned stand barred by limitation, those proceedings can be challenged before this Court, an alternative remedy notwithstanding. Finally, when an intricate interpretation of a provision is involved, the rule of alternative remedy, the learned Senior Counsel adds, cannot curtail this Court’s adjudicatory power. To support his contentions, he has relied on Whirlpool Corporation v. Registrar of Trade Marks1 , Popcorn Entertainment v. City Industrial Development Corpn.2 , M.P.State Agro Industries Development Corpn. Ltd. v. Jahan Khan3 , Godrej Sara Lee Ltd. v. Assistant Commissioner (AA)4 and Madras Bas Association v. Union of India5 .