From Professore Andrea Ortolani, in comments, a note of commonality in between Justice Ikadatsu Junko, who on Monday ruled unconstitutional and invalid the elections held in the Hiroshima #1 and #2 House of Representatives districts last year -- and Justice Katano Noriyoshi, who ruled yesterday that the Okayama #2 district election was unconstitutional and invalid (Link): both Ikadatsu and Katano are from the 30th lawyers' examination class.
Members of the 30th graduating class are on the cusp of retirement. Justice Ikadatsu is 65, mandatory retirement age for a justice. Katano, if he is not also in his final year, is probably close to it.
Nothing like approaching retirement to ease fears of retaliation and exclusion. Nothing stands in the way of your getting a full pension; no one can threaten you with exile to the sticks (Justice Ikadatsu served in Gifu, Tsu, Tokyo, Nagoya, and Okinawa before her present posting). No sempai can pressure you to not rock the boat. Having no hope of higher appointment, you are liberated from the need to be popular with your peers.
Revolution -- t'is a priviledge of the old.