President Trump’s sweeping tariffs will be scrutinized by the Supreme Court on Wednesday, placing the president’s most significant economic initiative into the justices’ hands.

The main question looming over the case is whether Trump can use emergency powers to justify his worldwide levies as he seeks to transform global trade — an untested expansion of executive authority.

An appeals court’s 50-year-old decision to Trump’s own statements about his banner policy could come into play.

Here are five things to watch for out of the arguments.

The impact of Nixon tariffs

Trump has justified the bulk of his sweeping tariff agenda by pointing to the International Emergency Economic Powers Act (IEEPA), which gives the president power to “regulate” imports in response to certain emergencies.

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