Limited Andrew Johnson's power to remove cabinet members.
During Andrew Johnson's presidency, he removed appointed officials (including cabinet members) that were trouble for him, especially those with Radical Republican-leaning tendencies. Congress had gotten fed up with this and decided to limit his power to remove anyone unless he got consent from the Senate.
Johnson acted against this law and removed Secretary of War Edwin Stanton. This was a clear violation and eventually led to his impeachment trial. The act was essentially crafted because Congress knew he would violate it and they could impeach him for it.