But since there isn't one, I prefer to avoid having to be the enforcer. My favorite place to avoid that duty is the walkway between my office and the cafeteria. There are glass doors at either end so you can always see if someone's behind you, and the way I like to do it is to walk quickly, open the door just far enough so I can slip in, and let it close behind me.
You're supposed to be polite and hold doors for people, but at work you're supposed to act like a guard if you do that. It's so satisfying to do neither.