Discipline in Open Source Projects?

An anonymous reader asks: "I've recently been elected (with another project member) to lead an open source project that we helped start several years ago. One of our goals as project leads is to implement some way to discipline project members who are disruptive to the project. In the past, the project has been slowed by flames, trolls, and even filibustering. Everyone says they want to work together, but some refuse to accept majority opinion. This passive-aggressiveness, coupled with growing despair on the part of other members, would have caused the project to dissolve if a vote had not taken place to elect new leadership (which the project has been lacking for some time). As co-leads we want the project to continue and grow, and we welcome all opinions, but how can disruptive members be told 'enough is enough'? We've read Ubuntu's Code of Conduct, but how can it or something similar be enforced?"