What were pirate codes?

The pirate code grew out of the experience of most pirates in previous naval or merchant service under harsh conditions and even harsher men as commanders, which left an indelible impression and desire to create a more secure and equitable environment aboard ship....

Pirate Code of Conduct

In the second half of the 17th century, buccaneers began operating under a set of rules called the Chasse-Partie, or Charter Party, which for a season even held legal weight in the Jamaican court system. This code of conduct later grew into the Articles of Agreement (pirate's code), which basically explained the standard operating procedures for all pirates involved...
Read more at The Pirate's Realm.