Codes of Conduct are introduced to push us back up the slippery slope that brought us to a point where personal insults and threats of violence are considered an acceptable part of public discourse.
Codes of Conduct are in place to protect everyone’s rights: They ensure a space in which a civil discourse can take place without anyone resorting to personal attacks and creating an environment that becomes inaccessible or actively hostile to participants or groups. Codes of Conduct ensure open spaces for freedom of expression.
I had the honor to meet Morten Rand-Hendriksen at WordCamp US, and we spent some time together discussing Freedom of Speech and Codes of Conduct. I believe he just published a masterpiece on the topic on his blog.
If you are part of an online community of any sort, you should do yourself a favor and read the entire post.