A conservative legal group is suing the Trump administration in Texas over the president”s tariffs on Chinese imports, alleging that they were unilaterally imposed through an “unlawful” use of an obscure emergency executive power.

The 24-page complaint filed Thursday by the New Civil Liberties Alliance (NCLA) in the U.S. District Court in Austin alleges that the authority to impose such tariffs lies exclusively with Congress, not the president, and seeks a preliminary injunction enjoining their implementation and enforcement.

It is the second such lawsuit filed by the group over President Donald Trump’s levies.

“A tariff is a tax on Americans’ commerce with other countries. The Constitution assigns Congress exclusive power to impose tariffs and regulate foreign commerce,” the complaint states. “Presidents can impose tariffs only when Congress grants permission, which it has done in carefully drawn trade statutes. These statutes typically authorize tariffs only on industries or countries that meet specified criteria, and only under specified conditions, after following specified procedures.”

Such tariff-authorizing statutes, the plaintiffs say, require advance investigations, detailed fact findings, and a “close fit between the statutory authority and a tariff’s scope,” all of which they say were conspicuously ignored by the administration. The Trump administration is attempting to “bypass” such constraints by invoking the International Emergency Economic Powers Act of 1977 (IEEPA) in a manner that has never been done since that statute was passed nearly a half-century ago, the complaint alleges.

According to the nonprofit group, the IEEPA grants the executive sweeping authority to quickly combat international economic crises, permitting the president to “order sanctions as a rapid response to international emergencies.” However, the NCLA asserts that the emergency statute does not allow the president to usurp the legislative branch’s control of the country’s purse strings through the unilateral imposition of tariffs.

“These unlawful tariffs are a presidential power grab that usurps Congress’s right to control tariffs and upsets the Constitution’s separation of powers,” Andrew Morris, Senior Litigation Counsel for the NCLA said in a statement. “They are especially crushing to small businesses — including our clients in this case. The court should hold the tariffs unlawful and strike them down.”

Looking to the terms in the IEEPA, the suit argues that even when viewed in a light most favorable to Trump, his administration’s tariffs still run contra to the law because the IEEPA limits presidential actions to those “necessary” in addressing a specific emergency. In this case, the president declared an emergency over Chinese opioids being brought into the country and its trade deficit with the U.S.

“But the Tariff Executive Orders show no connection between these problems and the tariffs he ordered — much less that the tariffs are ‘necessary’ to resolve those problems,” the complaint states. “The means of across-the-board tariffs do not fit the ends of stopping an influx of opioids or ending trade deficits, and is in no sense ‘necessary’ to those stated purposes. While the ’emergencies’ the President has declared are not challenged here, the ‘fit’ of the tariffs to the declared emergencies does not meet the requirements of IEEPA.”

The NCLA filed the complaint on behalf of outdoor cooking manufacturer FIREDISC, the nonprofit Game Manufacturers Association (GAMA), and an individual named Ryan Wholesale, who manufactures timber trusses and other wood products. The suit alleges that the “unconstitutional” tariffs will force the plaintiffs to pay more, thereby driving up their costs as well as the prices for their customers.

Plaintiffs argue that Trump is the first president to ever use the emergency statute as a means of imposing tariffs, a fact they say is “not surprising” because “the statute does not even mention tariffs, nor does it say anything else suggesting it authorizes presidents to tax American citizens.”

“Someone gave the President very bad legal advice,” NCLA President Mark Chenoweth said in a statement accompanying the lawsuit. “No prior administration in the nearly 50-year history of the IEEPA thought that it empowered the President to impose tariffs unilaterally. By doing so now, this administration has revived the specter of ‘taxation without representation’ over which the American Revolution was fought.”

The first lawsuit filed by the group challenging Trump’s tariffs has been transferred to the U.S. Court of International Trade in Manhattan.