The Anti-Criminal Code Effect Area (アンチクリミナルコード有効圏内 anchikuriminaru kōdo yūkō ken'nai) is any zone of player safety in the VRMMORPG Sword Art Online. Most of the settlements in SAO have this. More literally translated as "within the area of effect of the Anti-criminal Code", it is usually called the Inner Area (圏内 ken'nai) in-game, and is intended to allow players to recuperate and get prepared for another dungeon run, as well as to give them a way to safely practice.

Mechanics

The Inner Areas are situated within the main districts, which is to say from the city's center to its gates, and from the street level up to the base of the next Floor. The moment a player enters this space, its protection effect activates and a player HUD notification pops up. Upon leaving, the warning saying "Outer Field" (圏外 kengai) appears.

A player's presence in the Anti-criminal Code Effect Area prevents them from suffering from any and all offensive actions. For example, even an attempt to cleave a player with a melee weapon will be blocked with an impenetrable barrier, so the attack will cause a purple system effect and an unpleasant knockback effect — the blow will definitely be felt, but it is impossible to lose any hit points, not to mention die from that. No poison or any other damage-over-time items will work, either, and stealing a player's items is also rendered impossible. However, their gear may sustain damage even in the Inner Area, including breaking a sword or piercing a set of armor.

Importantly, the attacker's status color will remain Green if the attack happens in an Inner Area.

Duels

This functionality allows two players to check their damage dealing rate (DPS) or settle a heavy score, disabling the Inner Area effect by mutual agreement when both players accept the prompt. This is the only way to deal damage or even kill a player within the area.

There are three types of duels.

• In the First Strike Mode, the duel is decided with the first hit landed.
• In the Half-Damage Mode, the duel ends when one of the players loses half of their hit points.
• In the Total Loss Mode, the duel ends with a player's death, which is why nobody would choose this mode willingly in the game where a death is permanent, including the player's real body.

Interestingly, even if the players go with the Half-Damage Mode, the HP may easily fall way below half if the finisher is a critical hit, and so the largest portion of the duels are the one-hit First Strike ones.

It is also possible to admit defeat and surrender, thus ending the duel.

Orange Players

The Inner Area becomes dangerous to Orange players, too (not in all SAO media). As soon as an Orange player triggers it, multiple NPC guards will rush in to attack them, effectively banning entry. Restoring the Green status is the only way to return to the safe zone. Player Killers (PKs) cannot return to the Green status no matter what (not in all SAO media) and so they can never enter a settlement, which spares the players from a lot of headache.

Caveats

Although the safety system in SAO is expansive, there still are ways for a mischievously-inclined player to harrass the others.

Several players together could use their own bodies to prevent somebody from passing through ("blocking") or surround a person and control their movements that way ("the box").

Furthermore, as Asuna once proved, it is quite possible to bully a player by simply attacking them repeatedly and using the knockback's chilling effect.

There have even been murder cases in which PKs would challenge sleeping players to a Total Loss Duel and then move their finger towards the OK button, thus disabling the Code. In other cases, they used stretchers to carry an unconscious player to the Outer Field, and attacked there, free from the Anti-criminal Code's aegis. In addition, one could set up a Teleport stone to a gate right in the middle of a deadly high-level area and trick the victim into activating it.

References

Anti-criminal Code Effect Area - Fan Wiki
用語集(SAO) - @wiki