Muckamuck, I'm no journalist, but I helped create the system, so I'll try to explain! 

Each time a person comments, they must rate 3 comments from others—on each one, they first rate for quality, and then for civility. When you're still new, we ask you to also rate *your own* comment, and give you a chance to edit it before submitting (in case you have second thoughts).

Your comment is then reviewed by others in the same way. The number of people who review your comment varies, depending on what our backend algorithms "learn" from the initial reviews of it, and what they "learn" about how you reviewed the comments of others. The comment is then either published or withheld. I can't get much further into it (that's a lot of our "secret sauce"!), but I can say: we've worked hard to prevent cheating and bias. 

Let me know if that makes sense, or if I can answer any questions!