There's what the law says. Then there's the law that gets applied. Why do we view the former so differently to the latter?

So - quick pop quiz. What is the maximum speed you can travel on New Zealand's open road without incurring legal sanction?

If your answer was anything other than "it depends", you failed. Because, as the police's recent Queen's Birthday speeding blitz indicates, the speed at which you may drive without getting in trouble with the law jumps around all over the place.

Sure, there are signs that say "100" scattered along the edge of our highways and byways - some of them on ridiculously twisting stretches of road that only experienced rally drivers really should travel on at more than 70 km/h. But you'd be silly to assume that those signs indicate the speed you are permitted to drive at.

First up, all posted limits are superseded by a general requirement to travel at a "safe" speed. Traveling "at a speed or in a manner which, having regard to all the circumstances, is or might be dangerous to the public or to a person" breaches a legal duty. And it doesn't matter if the speed you are traveling at is lower than the posted maximum for that stretch of road - driving at any speed deemed for any reason to be "dangerous" breaches the law and can be punished. What then constitutes a "dangerous" speed often gets decided in retrospect; you get involved in a crash (or near crash), and ipso facto your speed was dangerous.

Of course, the contrary doesn't apply. If you drive at a speed that is greater than the posted maximum, then you technically commit an offence even if your speed is not "dangerous" having regard to all the circumstances. (I guess the theory is that as it is unsafe for anyone to go over 100 km/h in any conditions on any road, you should face potential legal sanction for doing so - but I'm not sure this theory stands up to a cruise along the Ida Valley-Omakau Road on a clear summer's day.)

But here's where things get somewhat tricky from a jurisprudential standpoint. Yes, the formal legal rule is clear: "drive at more than 100 km/h (or 80/70/50 depending on the speed zone) and you commit an offence." However, everyone knows that you can exceed that speed by some margin without running any risk of being pulled over by the police and sanctioned.

How do we know that? Because the police themselves tell us what their enforcement policy is. There is a standard 10% tolerance given to speeding drivers, meaning that tickets hardly ever get issued to people going less than 110 km/h. Consequently, 110 km/h has become the de facto open road speed limit.

(This near-total elision of the "enforced" limit with the "legal" limit is evidenced by a story my mother told me about a friend of hers who complained bitterly about the police ticketing her for traveling at 115 km/h, as she was "only going 5 km/h over the limit.")

However, if it is the case that the police's announced enforcement practice effectively determines the speed people may drive at, then isn't the consequence of their Queen's Birthday announcement (as well as earlier announcements like this one) a change in the law by press release?

I'll grant that the police's changed policy has no formal implications for the legal rule, as would be the case if the police announced they will start ticketing anyone driving at 95 km/h on the open road. You may, conditions always permitting, lawfully travel at 100 km/h on the open road, irrespective of anything the police say about that. A completely risk-averse driver can thus avoid potential legal liability by keeping their speedometer beneath that mark.

But many (most?) of us are not completely risk-averse when it comes to our speed. We drive up to the line of what we can get away with, not what the paper rule says. Meaning that on Thursday last week (and then again on the following Tuesday) we were able to drive at 109 km/h without fear of sanction, but Friday through Monday we only could go at 104 km/h.

Now, I accept there were perfectly good reasons for the police wanting to lower the average driving speed over the holiday weekend. I'm not a "it's all about revenue" conspiracy theorist, nor do I deny the basic laws of Newtonian physics. And who could argue with the weekend's outcome (although the link between the police's policy shift and that outcome are disputed by some)?

What is interesting, however, is the apparent ease with which the police can change the effective rules on speed, compared to the convoluted process that would have to be followed were the formal rules involved. A proposal to lower the legal, on the books, speed limit  from 100 km/h to 95 km/h would necessitate all sorts of consultation and public notice, stretching over months. The rule change would then need to be made by the Governor General in Council, before being officially Gazetted. And at the end, the police might announce the 10 km/h tolerance remains, meaning an effective speed limit of 105 km/h.

Compare this to how readily the effective speed limit can be changed to 105 km/h by the police themselves. The police decide that the holiday road toll needs to come down, and with an operational decision and media release they hive 5 km/h off the speed at which people can drive before the law will intervene. And no-one really bats an eyelid at this.

This issue of enforcement discretion is not unique to road transport, of course. The gap between "what the law says" and "how the law is applied" exists in a huge number of areas. Take the smacking of children, for example, or the rules governing the use of money at election time. Or, in the UK context, experimentation around how to deal with cannabis users.

What we don't see much of, however, is interest from the legal academy about how those sorts of decisions actually create the legal regime that people live by. Give us a statute, regulation or court case, and we'll fill pages of prose on its implications. But a policy decision by an enforcement agency, no matter how far-reaching, sails by us unremarked.

I don't know why that is. But I'm sure it can't be a healthy approach to the law.

Comments (12)

by william blake on June 10, 2010
william blake

Do you know if some people are still fined for breaking the posted limit within the tolerance de jour, Andrew?

The most common road side ticketing scene seems to involve a young man with a cap on ( unually with a bored looking girl chewing gum and twirling a lock of hair absentmindedly) or a skyline full of 'nesian boys.

I hope they have not been pulled over for speeding at 53km/h especially around here in West Auckland, where if you drive at less than 55km/h you loose sight of the following cars' headlights in the rear view mirror.

by Draco T Bastard on June 10, 2010
Draco T Bastard

What you seem to forget is the reason for the discrepancy between the legal limit and the enforced limit and that comes down to the hardware involved. Nothings perfect. So, to accept that the laser/radar measuring device used by the police may be out by a couple of km/h and that the speedometers in the cars will also be out by a couple you add a small discepancy between the legal limit and the enforced limit. As technology improves and manufacturing tolerances get smaller you decrease that discrepancy.

Really, the discepancy should have been decreased 5, or even 10, years ago.

by Kyle Matthews on June 11, 2010
Kyle Matthews


Police vehicles and speed measuring devices are regularly tested and calibrated. Cars regularly used for speed measuring will have a little card inside them indicating how their car is out by 1 or 2 km/hour at the various speeds.

This is nothing new, they've been doing it for decades. The new measuring devices are very accurate.

by stuart munro on June 11, 2010
stuart munro

There's quite an interesting comparison available on innercity speeding rates between Nelson & Christchurch. Nelson has a reasonably functional traffic flow, so 'offending' is considerably less per capita. But accident rates are essentially similar - the only difference is how much money our charming uniformed parasites collect. - In Christchurch, truckloads.

by Tim Watkin on June 11, 2010
Tim Watkin

William, I've heard of people being ticketed for 53 km/h, which is within the 10% allowance. So it's hardly consistent.

Andrew, if as you say, that ipso facto being in a accident means you were driving at a dangerous speed, what does that say about those police stats when they say speed was a contributing factor in X% of crashes this weekend (as opposed to tiredness, alcohol etc)? By your definition, speed would be a contributing factor in 100% of crashes.

by Andrew Geddis on June 11, 2010
Andrew Geddis


I guess I mean something like this. You're driving in a rainstorm along an open road (100 km/h zone), with reduced visibility. What is a "safe" speed to drive at? You slow to 80 km/h, but rounding a corner there is a car stopped on the road - you stomp on the brakes but slide into it. I suspect (although not being an expert on traffic law am prepared to be proven wrong) that a defence "I thought I'd slowed to a safe speed" would not work here - the fact that you had an accident (couldn't avoid the stopped car) shows your speed was dangerous in the conditions.

by william blake on June 11, 2010
william blake

So the speed limit is the one that is written on the packet; or it is dependan on, age, gender or ethnicity or just on the mood of the traffic cop.

Speaking of calibration; I think it is Sweden that has calibrated the speeding fine incurred to the drivers income; an inequity that has always puzzled me; the look of dismay on the driver of the clapped out corolla compared to the look of impatience from the M3 owner.

by Greg Dawson on June 12, 2010
Greg Dawson

Wikipedia says Finland topped out the highest speeding fine ever due to a system of ticketing scaled to last known income.

Would be an interesting system to apply, not just to speeding fines but all monetary penalties - a percentage of income instead of a flat rate would be fairly progressive.

Of course we'd need to figure out some way to reconcile reported income with actual income to keep it from being exploited, but that's a problem we've got to face up to anyway for tax reasons.

by Graeme Edgeler on June 12, 2010
Graeme Edgeler

Would be an interesting system to apply, not just to speeding fines but all monetary penalties - a percentage of income instead of a flat rate would be fairly progressive.

The system is already somewhat in use in New Zealand, in the military justice system. The maximum fine for a service member for an offence against the Armed Forces Discipline Act is 84 days basic pay.

by Greg Dawson on June 13, 2010
Greg Dawson

Sweet, so all we need is mandatory military service and we're sorted :P


by Ian MacKay on June 16, 2010
Ian MacKay
While driving in Abudhabi UAE on those beautiful 3 lane highways, large signs read speed limit 100kph. Next are the large signs which say radar set at 120kph. So we travelled at 119kph. Often we were overtaken by Emarati cars travelling at between 140-190kph. On good roads it would be easy to travel at 150kph without being aware of speed.
by Andrew Geddis on June 17, 2010
Andrew Geddis

And, of course, there are the German Autobahns, which famously have no hard-and-fast speed limit on them. However, according to wikipedia:

"it is important to note that an advisory speed limit (German: Richtgeschwindigkeit) of up to 130 km/h always applies. In case of an accident while driving faster, a court can decide on shared liability due to the increased operational risk."

That makes for a nice compromise - "we won't punish you just for going faster than this, but if you do so and crash we may well hold you liable for your decision...."

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