The “three-pirate rule” is a method of delegating decision-making in a “swarm” or flat organization. Though he did not coin the phrase, it was popularized by Rick Falkvinge, who launched the Pirate Party movement in the mid-2000s.
The rule is basically:
if three “pirates” agree something is worth doing, and it is within the principles of the organization, they do not need to ask permission to act.
The rule was adopted by Pirate Party organizations around the world.
Falkvinge further extended this concept in his book Swarmwise – The Tactical Manual To Changing The World. From chapter 7:
We make decisions. We aren’t afraid to try out new things, new ways to shape opinion and drive the public debate. We make decisions without asking anybody’s permission, and we stand for them. Sometimes, things go wrong. It’s always okay to make a mistake in the Pirate Party, as long as one is capable of learning from that mistake. Here’s where the famous “three-pirate rule” comes into play: if three self-identified pirates are in agreement that some kind of activism is beneficial to the party, they have authority to act in the party’s name. They can even be reimbursed for expenses related to such activism, as long as it is reasonable (wood sticks, glue, and paint are reasonable; computer equipment and jumbotrons are not).