Marilyn-Joy Cerny has challenged the US government thousands of times during her 35-year career as a trade lawyer, enjoying an enviable record of recovering tariff money for importers whom Washington wrongfully charged.

“I have filed so many protests in my day, I joke with my team that Customs might be saying, ‘me think she doth protest too much’,” said Cerny, managing partner with law firm Sandler, Travis & Rosenberg. “Of my protest cases that I’ve had to take to court? I would say 95, 96 per cent [were successful]. But the Supreme Court may really erode my success rate.”

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Soybeans: China’s new bargaining chip in trade war with US?

Soybeans: China’s new bargaining chip in trade war with US?

Trump’s legal team, however, argues that the decades-old US trade deficit is a national emergency that justifies imposing tariffs on most of the world and that they are regulatory and not aimed at generating revenue.

Should the ruling go against Trump – the decision is expected within weeks, lightning speed by Supreme Court standards – Washington may have to engineer a giveback larger than the annual GDP of over 100 nations.