Just a few hours after President Trump declared a national emergency at the southern border, the American Civil Liberties Union (ACLU) announced Friday that it will file a lawsuit next week challenging the declaration.

“By the president’s very own admission in the Rose Garden, there is no national emergency. He just grew impatient and frustrated with Congress, and decided to move along his promise for a border wall ‘faster.’ This is a patently illegal power grab that hurts American communities and flouts the checks and balances that are hallmarks of our democracy,” Anthony Romero, the ACLU’s executive director, said in a statement Friday afternoon.

The ACLU said that it will argue in the lawsuit that the emergency powers Trump used to make the declaration cannot be used to build a border wall. Those powers were meant for “military construction projects, like overseas military airfields in wartime, that ‘are necessary to support’ the emergency use of armed forces,” the ACLU said in the statement.

It was widely expected that Trump’s decision to declare a national emergency in order to fund construction of a border wall would prompt legal challenges. Trump himself acknowledged in his Friday morning speech announcing the move that he will face lawsuits.