Why have a code of conduct
Help Establish Social Norms
An explicit code of conduct for a conference helps to establish social norms for that conference.
When attendees from varying backgrounds and experiences get together, it is not necessarily safe to assume that everyone's expectations of what is appropriate are in line with each other. 
Help Even One Person
If a published code of conduct helps even one person have a better time at that conference, it’s worth it.
Statement of Intent
A code of conduct makes it clear that the organisers have thought about how to ensure everyone has a positive experience, by joining a shared platform or attending an event the attendees implicitly accept the code of conduct as well.
Improve the Quality of Discussion
A prominently displayed code of conduct may improve the quality of discussion and encourage contributions. In a study of the subreddit /r/science researchers found that by posting rules made:
newcomer comments 7.3 percentage points more likely to follow the rules, increasing newcomer participation by 38.1%Posting Rules in Online Discussions Prevents Problems & Increases Participation
- Will it "put an end to misogyny and racism"?
- Put an end to? No. Reduce misogyny and racism? Very likely. Every such improvement counts. The arc of changing behavior is long, but we can work to bend it towards respect. (Paraphrased from "arc of" quotes).
The concerns quoted below, if not attributed, are normalized from private communications.
Unsure It Will Help
"I'm personally not sure that a public Code of Conduct will help."
There's some evidence that the *absence* of an explicit Code of Conduct makes women question whether they should speak or even attend a conference. E.g. Noirin Plunkett's experience:
- Conferences and dark alleyways (archived)
Subsequently O'Reilly adopted a Code of Conduct and Noirin Plunkett did choose to attend and speak at OSCON.
- 2011-07-26 : O’Reilly Announces Anti-Harassment Code of Conduct (archived)
Regarding IndieWebCamp, Rosemary Orchard said:
"If there were no CoC, I wouldn't be attending" 2018-10-07 chat logs
Also, if this uncertainty is the opinion of someone who is of the dominant demographic at tech conferences, ask them to ask any of their co-workers who are either not male, or not white, or not hetero if they think a public Code of Conduct will help or not, even a little.
Will It Have Opposite Effect
"Research suggests that publicly defining rules of behavior can actually have the opposite effect to that intended"
I (Tantek) have not seen any such research regarding conferences having a Code of Conduct, and I'd be very interested to see citations of any of it to try to understand how such a counter-intuitive opposite effect occurs.
Highlighting A Group Makes Them A Target
"Noting a particular group of people as a potential target of harassment may actually signal them out as different."
All the examples of Code of Conduct refer to attributes (like "gender") rather than a group of people (like "women"). In addition, they all cover numerous other attributes (age, sexual orientation, race, etc.) so none of them are noting just a particular group of people as a potential target.
Will Groups Feel More At Risk
"Noting a particular group of people as a potential target of harassment may actually make them feel more at risk."
All the first person blog posts written on this subject (e.g. Noirin's post) state the OPPOSITE. That is, that *lacking* a Code of Conduct makes them feel more at risk, and *having* a Code of Conduct helps them feel like the conference does care about them and their safety.
If there are posts that demonstrate otherwise, please share.
Will It Normalize Inappropriate Behavior
"An explicit code of conduct may have the effect of normalizing inappropriate behavior as it may imply that it's more prevalent that is actually the case."
It is good to be concerned with in general the potentially overall negative tone that a Code of Conduct can take.
The IndieWebCamp Code of Conduct tries very hard to frame and phrase the majority of its points in terms of positives, respect, good behavior, support, community etc.
By doing so (emphasizing what's positive), we can normalize the positive, while clarifying what the negatives are, how to avoid them, and what the consequences will be.
Happy to accept suggestions for improvement in this regard as well.
Would Rather Do Actions Than Say Words
"More interested in demonstrating commitment through actions, by ensuring a balanced conference line up, by promoting the event to as wide a range of people as possible, and by creating a warm and friendly culture of inclusivity at the event."
Actions do speak louder than words. But why not both?
A well written Code of Conduct can *add* to a warm and friendly culture of inclusivity at an event.
Any existing event that already works hard to provide a warm and friendly culture of inclusivity could make the event feel even warmer and more inclusive (and safer to those who have been harassed in the past) by publishing a Code of Conduct, warmly worded in the same manner as the rest of the event.
- Building Compassionate Communities in Tech - by Isaac Schlueter
- https://philsturgeon.uk/2016/07/23/talking-about-diversity-marginalization/ and https://philsturgeon.uk/2016/08/02/talking-about-diversity-conspiracy/
- Why should an event have one? Why should I choose to only attend events with one? from Ashe Dryden’s Codes of Conduct 101 + FAQ.
- 2013-01-07 “Free as in sexist?” Free culture and the gender gap
- The Tyranny of Stuctureless by Jo Freeman. Also applies to Organizers.
Once the movement no longer clings tenaciously to the ideology of "structurelessness," it is free to develop those forms of organization best suited to its healthy functioning. This does not mean that we should go to the other extreme and blindly imitate the traditional forms of organization. But neither should we blindly reject them all.