But he undermined the will of the people.
Violating the 'Will of the People' is an impeachable offense in communist dictatorships not Constitutional Republics.
(Denny Crane: "Sometimes you can only look for answers from God and failing that... and Fox News".)
The Constitution is the HIGHEST form of the Will of the People and it established the judiciary to bring ordinary law into accord with the Constitution. I believe this judge was wrong but not because he went against the will of the people. However the people of Nebraska cannot impose its will contrary to the Constitution.
There would have been no end to slavery if the will of the people had been consulted or even a Revolution since only about a third of them wanted independence.