President Andrew Johnson believed that this law was unconstitutional because it gave the Senate a power over his appointments that was not given to it by the Constitution.
The Constitution gives the Senate the right to approve or reject the people that the president nominates to a variety of positions. This includes all of the president’s cabinet members. The Congress extended this right to mean that it also had the right approve or reject the president’s efforts to remove cabinet members. In other words, the Tenure of Office Act said that the president could not remove someone from office without the Senate’s consent if that person had originally been approved by the Senate.
President Johnson believed this was unconstitutional because the Constitution does not give the Senate the power to prevent a president from removing a cabinet official. By taking such a right for the Senate, the Tenure of Office Act was, Johnson argued, unconstitutional. The Supreme Court agreed with Johnson, but not during his lifetime. It ruled the Tenure of Office Act had been unconstitutional in a case called Myers v. United States in 1926.