In Full Metal Panic! Fumoffu?, we see Hayashimizu Atsunobu, the Student Council President. When Sousuke addresses him, he always calls him "Your Excellency" and stands at attention.
He seems totally fine condoning Sousuke interrogating the thug who passed on the message that Chidori had been kidnapped (closing the blinds and not stopping Ren or Sousuke).
While in a school environment, he is a figure of authority, but he is hardly the highest authority with the teacher still above him, and Sousuke never uses similar terms for any teacher.
So why does Sousuke call Hayashimizu Atsunobu "Your Excellency"?