As I said on xFire, you can not get faction killed from another leader of another faction. The only people who may faction kill you is members in your faction who are Tier 1 or 0 (Head admins may faction kill you as well).
Faction Leaders can not be faction killed if they have not held their position for more than 2 weeks.
But: Faction owners / leaders (Godfather) may factionkill anyone at any time for any reason. OOC kicks do not count as FK. Admin uninvite does count as a FK.
To faction kill(FK) your leader, the co-leader, and 3rd in charge(Consig, ..) needs to be in on it, and be present during the FK.
You will also need approval from the head of illegal factions(for mafias) or head of legal factions(for GOV/LVPD/FBI/SASF/SDC) admin to go through with the FK. You are advised to get approval BEFORE you FK the leader. Bear in mind you need a VERY valid reason to FK a leader & permissions will not be handed out often or easily.