The firms signed a legal brief supporting Seattle-based Perkins Coie, calling the president’s actions a threat “to the rule of law.” The largest firms declined to sign.

The judiciary should act with resolve — now — to ensure that this abuse of executive power ceases,” the brief reads.

About a dozen Am Law 200 firms, including at least eight Am Law 100 firms, have signed on to the brief as well.

More than 500 law firms have signed on to an amicus brief filed Friday in support of Perkins Coie’s challenge to President ...