bbPress.org

You could use this plugin:

https://bbpress.org/plugins/topic/terms-of-service/

CC is not really about the type of behaviour to expect on a forum though. CC is for licensing. Why not find T&C you like from another forum and copy the best ideas?

Some inspiration:

http://www.fourhourworkweek.com/blog/2008/08/13/total-immersion-how-i-learned-to-swim-effortlessly-in-10-days-and-you-can-too/#respond

http://mlb.mlb.com/fan_forum/msgboard_guidelines.jsp

http://www.google.com/search?q=forum+terms+and+conditions

But honestly, just tell people what you expect and what you’ll allow. Customize it for your site.

See the FAQ for some suggested URLs:

https://bbpress.org/plugins/topic/terms-of-service/faq/

The problem is legal TOS has to be adjusted per site.

this is the most obvious “free” one but it has to be adapted:

http://wordpress.com/tos/