The material below is Open Game Content from a 3PP Source
Combat Expertise (Combat)
You can increase your defense at the expense of your accuracy.
Prerequisite: Int 13.
Benefit: You can choose to take a –1 penalty on melee attack rolls and combat maneuver checks to gain a +1 dodge bonus to your Armor Class. When your base attack bonus reaches +4, and every +4 thereafter, the penalty increases by –1 and the dodge bonus increases by +1. You can only choose to use this feat when you declare that you are making an attack or a full-attack action with a melee weapon. The effects of this feat last until your next turn.
The material below is Open Game Content from the System Reference Document.
COMBAT EXPERTISE [Combat]
Prerequisite: Int 13.
Benefit: When you use the attack action or the full attack action in melee, you can take a penalty of as much as –5 on your attack roll and add the same number (+5 or less) as a dodge bonus to your Armor Class. This number may not exceed your base attack bonus. The changes to attack rolls and Armor Class last until your next action.
Normal: A character without the Combat Expertise feat can fight defensively while using the attack or full attack action to take a –4 penalty on attack rolls and gain a +2 dodge bonus to Armor Class.
Special: A fighter may select Combat Expertise as one of his fighter bonus feats.
