India, Aug. 30 -- A US appeals court on Saturday ruled that most of President Donald Trump's tariffs are illegal, dealing a major blow to one of his key economic policy tools. Despite the ruling, the tariffs will remain in effect until October 14, allowing the administration time to appeal the decision before the Supreme Court.

In its judgment, the US Court of Appeals for the Federal Circuit in Washington, DC, said Trump had overstepped his authority by imposing the tariffs under emergency powers laws.

"The statute bestows significant authority on the President to undertake a number of actions in response to a declared national emergency, but none of these actions explicitly include the power to impose tariffs, duties, or the like, or t...