The American Institute for International Steel (AIIS) on Wednesday filed a lawsuit challenging President Trump's tariffs on imported steel and aluminum.

Joined by two member companies in the lawsuit, the trade association asks a court to declare that Trump's 25 percent tariffs on steel are unconstitutional because, it charges, they represent an improper "delegation of legislative power to the president," and violate the doctrine of separation of powers and the system of checks and balances.

The lawsuit, filed in the U.S. Court of International Trade, asks the court to block the Trump administration from enforcing the tariffs.

While many AIIS member companies do not pay the tariff directly, they are affected because the amount of steel imported is decreasing due to the tariffs.

According to the complaint, AIIS is concerned that the tariff increase will negatively affect its member companies by forcing them to raise prices, which would result in losing business and having to lay off workers.

Trump implemented the tariffs on imported steel and aluminum in March, and has faced backlash from companies who have said the tariffs are causing them to struggle financially.