At the centre of this setback to Trump is the Indian-origin American lawyer Neal Katyal. 
At the centre of this setback to Trump is the Indian-origin American lawyer Neal Katyal. The US Supreme Court on Friday dealt a thunder blow to President Donald Trump as it struck down his earlier reciprocal tariffs that were imposed under the International Emergency Economic Powers Act (IEEPA).
In a 6-3 decision, the Supreme Court ruled that the IEEPA, which grants the president authority to regulate or prohibit certain international transactions during times of national emergencies, does not authorise the president to impose sweeping tariffs.
At the centre of this setback to Trump is the Indian-origin American lawyer Neal Katyal.
Here's what you need to know about Neal Katyal
Who is Neal Katyal?
Born in March 1970, Katyal is a prominent American attorney, legal scholar and former Acting Solicitor General of the US under the Obama administration. He has argued more than 50 cases before the US Supreme Court and has surpassed Thurgood Marshall for the most cases argued by a minority attorney.
At present, Neal Katyal is a partner at Millbank LLP and the Paul and Patricia Saunders Professor of National Security Law at Georgetown University. He has also served as a special prosecutor in the Derek Chauvin trial.
What are Neal Katyal's educational qualifications?
He studied at Loyola Academy, a Jesuit Catholic high school in Illinois. In 1991, he graduated from Dartmouth College, where he was a member of the Dartmouth Forensic Union. Following this, he attended Yale Law School and studied under Akhil Amar and Bruce Ackerman.
After receiving his Juris Doctor (J.D.) in 1995, he clerked for Judge Guido Calabresi of the US Court of Appeals for the Second Circuit and then for Justice Stephen Breyer of the US Supreme Court.
What were his arguments against Trump's reciprocal tariffs?
Katyal argued that tariffs were a form of taxation, adding that under Article I of the US Constitution, the "power of the purse" of the exclusive authority to impose taxes and duties belongs to Congress and not the President.
He highlighted that the IEEPA does not contain the word "tariff" or "duty". Even though the law allows the President to freeze assets or block financial transactions in times of national emergencies, Katyal mentioned that it does not implicitly grant POTUS the power to levy broad-based import taxes.
Besides this, he underscored that the case was about protecting the separation of powers. Neal Katyal argued that allowing the President to unilaterally impose "unbounded tariffs" at will would represent a "transformative expansion" of executive authority that the law never intended.
He also challenged the administration's use of trade deficit and fentanyl crisis as justifications for acting under IEEPA and bypassing Congress for economic policy.
What did he say on the Supreme Court ruling?
Commenting on the US Supreme Court's Friday ruling, Katyal described the tariffs imposed by Trump under IEEPA as "unjust, unconstitutional taxes".
He said that the case was always about the presidency and not "any one president". It has always been about the separation of powers, and not the politics of the moment," he added.
He told MS News that he went to the court on behalf of American businesses.
"I was able to go to court -- the son of immigrants -- and say on behalf of American small businesses, 'Hey, this president is acting illegally.' I was able to present my case, have them ask really hard questions, and at the end of it they voted and we won. That is something extraordinary about this country," he said.