President Donald Trump’s sweeping new tariffs, including a 10% blanket levy on all imports, officially took effect this weekend — and legal pushback is already underway, The Wall Street Journal reported on Sunday.

The markets have continued to sour on President Donald Trump’s tariffs on nearly all imports to the United States. Major stock indices have been on successive roller coasters of daily trading, reacting positively to indications the president might relent but then quickly falling after Trump signals he plans to stay his course.

Two legal organizations frequently associated with and financed by conservative causes have filed litigation challenging the basis of Trump’s import tariffs, and argue the levies usurp Congress’s power of taxation.