Culpable violation of the constitution
For purposes of impeachment, "culpable violation of the Constitution" is defined as "the deliberate and wrongful breach of the Constitution." Further, "Violation of the Constitution made unintentionally, in good faith, and mere mistakes in the proper construction of the Constitution, do not constitute an impeachable offense."
As the highest magistrate of the land, he should have known better.
The law should not be breached.