Call it what you will - honor code, family pledge, whatever (or don't call it anything at all), but take a few minutes to create a short list of how you will treat each other. Here are a few prompts:
1. How or when will you fight? Disagree?
2. How will you speak to each other?
3. Any "code" words, signs, messages that you can give so that the other knows to back off?
Take a bit to think about what kind of atmosphere you want to promote in your home. What example do you want to set for your kids?
Then realize that you are the ones in charge of how people are treated in your home. And I'd say invite your spouse to participate in this one. If you'd prefer not to, then pledge it to yourself. And then share it here!