> I started wondering if there's a way for citizens to push the issue that these tarrifs are unconstitutional.

Anyone who imports and is assessed a tariff would have personal standing to sue, arguing that the tax is illegal. I think there are some procedural requirements first to e.g. formally complain, but the dispute would eventually get its day in court.

However, these tariffs are being applied at least under a thin veneer of law regarding declared emergencies. It's clearly beyond the intent of the law for Trump to do this, but it's hard to draw a bright line between this and (e.g.) ambitious environmental regulation.