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.

At issue is a nearly-50-year-old law, the International Emergency Economic Powers Act, that Trump is citing to impose tariffs.

A nonprofit group said the president misapplied a law in imposing those levies and portrayed its filing as the first lawsuit to challenge the Trump administration over its tariffs.