The Pirate King, also referred to as King of the Brethren Court, was the elective monarch and leader of the Brethren Court. The Pirate King was to be holder of great amount of power, he would lead the pirates around the globe. To be elected Pirate King, the plurality of the Pirate Lords were required to vote on a single candidate. This process was fraught with difficulty as it was common for each Pirate Lord to vote for themselves.
The Pirate King was given authority not available to Pirate Lords, such as the ability to declare war and parley with adversaries, as stated in the Pirata Codex. Elizabeth Swann was declared Pirate King during the fourth meeting of the Brethren, after Jack Sparrow seconded Elizabeth's own vote, while the remaining Lords voted for themselves. Elizabeth was the first Pirate King to be elected since the first Brethren Court. The Pirate King is shown to have far more power than the Pirate Lords, as seen when Elizabeth traded Jack Sparrow for Will Turner, against Barbossa's wishes.