executioner_validity_trigger

executioner_validity_trigger = {
	# base_court_position_validity_trigger = { EMPLOYER = $EMPLOYER$ } can be imprisoned
	NOT = { is_at_war_with = $EMPLOYER$ }
	is_adult = yes
	is_landed = no
	custom_tooltip = {
		text = NONE_NOT_THE_SPOUSE_OF_CHARACTER_COURT_POSITION
		NOT = { is_spouse_of = $EMPLOYER$ }
	}
	OR = {
		custom_tooltip = {
			text = has_imprisonment_reason_no_subject
			$EMPLOYER$ = { has_imprisonment_reason = prev }
		}
		custom_tooltip = {
			text = is_imprisoned_court_position_executioner
			trigger_if = { # Imprisoned characters should only be valid if they aren't already the executioner
				limit = {
					is_imprisoned = yes
					NOT = { has_court_position = executioner_court_position }
				}
				is_imprisoned_by = $EMPLOYER$
			}
		}
		custom_tooltip = {
			text = has_strong_hook_no_subject
			$EMPLOYER$ = { has_strong_usable_hook = prev }
		}
	}
	custom_tooltip = {
		text = none_does_not_have_a_full_time_job
		trigger_if = {
			limit = { NOT = { has_court_position = executioner_court_position } }
			court_position_does_not_already_have_a_job_trigger = yes # This positions is considered a job, and cannot be held at the same time as another similar position
		}
	}
	court_position_can_be_combatant_tt_trigger = { EMPLOYER = $EMPLOYER$ }
}

As written in game/common/scripted_triggers/00_court_position_triggers.txt.