Since I first started driving as a teenager, I have always followed the same formula for how fast I drive. If I’m driving on city streets, I drive no more than four miles over the speed limit. If I’m driving on the highway, I drive no more than nine miles over the speed limit.
But this isn’t just my maximum speed; it’s my habitual speed. If I’m driving more than a minute or two in the same direction, I always set cruise control at this speed and leave it there.
With this formula, driving in more than 30 states and over 200,000 miles, I’ve never received a speeding ticket. I’ve never even been pulled over. This is true even though I am almost always driving at a speed that is in technical violation of the law. I have probably driven by police officers over 500 times while violating the law, and the police officers that saw me have never sought to enforce the laws.
I’ve discovered a driving Schelling point where the legal norms differ consistently from the written laws.
This is a good illustration of the difference between laws and legal norms. The former refers to the literal language of the rules that govern our societies and the latter refers to the unwritten but generally understood rules that determine when those persons who are responsible for enforcing the legal rules actually seek to enforce them against violators.
Let’s call the legal speed limit n1, but the actual speed where police officers tend to enforce the speed limit n2. Since n2 is the speed where the law is actually enforced, why not set the speed limit at n2? Wouldn’t that be more transparent and fair?
Some might think that if we raised the speed limit to n2, that this would encourage drivers to go faster, to a newer, more dangerous speed, n3.
But that’s not true. If police rigorously enforced the new speed limit, n2, drivers would adjust their behavior. There’s no reason speed limits couldn’t be like the playing boundaries in a game of football or basketball. Toe touches the line, and it’s out of bounds. No margin for error.
The reason for the discrepancy is that law enforcement wants to have wiggle room to enforce the rules. It is a well-established principle that laws that are too vague may be deemed unconstitutional, because they invite arbitrary or discriminatory enforcement. But there is nothing unconstitutional about failing to enforce a clear law sometimes and enforcing the law other times. Law enforcement enforces the rules this way because they want a certain amount of wiggle room to enforce what they perceive to be suspicious behavior.
This is why a lot of questionable, arguably discriminatory law enforcement actions revolve around technical enforcement of laws that are not usually enforced.
By setting up a system where most norm-abiding citizens are in frequent violation of existing laws, law enforcement has greater discretion to enforce laws as they see fit. If a police officer pulls you over because you were driving two miles over the speed limit and later discovers you were driving while drunk, you can’t argue that it was illegal for her to pull you over for that reason. It was just unusual.
This Zone of Law Enforcement Wiggle Room – the zone between n1 and n2 – is where so much of the controversial and disputed tensions in our society can be found. Beyond speed limits, examples include drug enforcement, political dishonesty, international dispute resolution, and immigration policies.
By creating a Zone of Law Enforcement Wiggle Room, those responsible for enforcing laws have more power. Strict enforcement of laws would eliminate law enforcement discretion and make it more obvious when law enforcement was acting inconsistently. The very act of inconsistency would be a violation of the law. As such, a consistent regime of loose enforcement is the best mechanism for ensuring that law enforcement maintains its discretion.
Further reading: David Friedman, A Positive Account of Property Rights. Social Philosophy & Policy, volume 11, number 2 (Summer 1994).
 A couple of years ago I was driving around Spain, and I followed the driving rules that have served me so well driving in the United States. But when I got home to Colorado, I got three tickets in the mail for driving slightly over the speed limit. I’m not sure if it was because I was a foreigner, or because I was driving a rental car, or because that’s the way the law is enforced there, but because in Spain there was no gap between the written law and the enforced norm, I’m about 500 euro poorer than I would have been otherwise.
 Unless it can be proven that law enforcement consistently enforced the law with discriminatory intent or that enforcement had a discriminatory impact. But this is very hard to prove (and the reason why segregation lasted for as long as it did).
 I don’t think that law enforcement does this for cynical or malevolent reasons. I think it’s a system that has evolved over time because it works for them.