And so we come to parking spaces in snowy places. Normally, you appropriate a parking spot by putting your car into it. All available spots are up for grabs. Because cities refuse to charge market-clearing prices for parking, there's excess demand that's solved by first-come-first-served queueing.
But suppose you've had a snowstorm. None of the parking spaces are available because they're all snowbanks. When you shovel out a spot, you have homesteaded it. At least a little bit. You've mixed your labour with the uncleared snow and have some ownership right to that space, at least for a little while. Standard practice in many North American cities then allows the clearer of the space to own it and to signal ownership by the leaving of an appropriate marker. A chair, a road cone, a barrel - something big enough to say "Hey, I cleared this spot. I know you could move the barrel and take my spot, but you'd be a total jerk if you did."
The Boston Globe tells me [HT: @BKDrinkwater] that this practice has even been recognized in official city practice [I don't know if it's a bylaw.] If the city declares a snow emergency, you can set out a marker owning a space for 48 hours after the end of the snow emergency. So you get a limited homesteading right. But the city's practice doesn't put in a homesteading requirement.
And so we can get problems where the state comes in to enforce a pre-existing social norm through official practice. What if you declare a snow emergency, and it doesn't snow? By the city's rule, you can then appropriate any old parking spot without having mixed your labour with it. Or can you?
I love the induced prisoner's dilemma. I also love that it takes an entrepreneur to initiate the revolution. Everybody fears retribution so nobody wants to be first mover against the norm-breaker, and because everybody else fears that the game unravels, they all put out space savers. Until Captain Cone comes around, pushing everybody back to the better equilibrium.
You could likely write a political economy masters thesis on social norms around this issue: how the institution evolved in different cities, how it interacts with city practice - whether parking wardens leave the cones there or biff them, and what happens when code conflicts with norm.
* Cat has homesteaded nothing [very mildly NSFW].