An impeachable offense is whatever a majority of the House and two thirds of the Senate say it is. No judicial review (but the Chief[L] gets to count the votes wearing an extra-fancy robe).
The first is easily attainable, I would hope. Not so much the second.
“An impeachable offense is whatever a majority of the House and two thirds of the Senate say it is...”
This president could slaughter 20 people on the floor of the House with an “assault rifle”, and Harry Reid would not allow an impeachment/conviction vote in the Senate.