Halfway Decent Study, Wrong Conclusion

Much has been made of a recent Australia and New Zealand study finding that teens who drink regularly (at least once a week) before the age of 17, and especially by age 13, are statistically more likely to go on to drink heavily, become alcohol-dependent, drive drunk, use/abuse other substances, and smoke cigarettes during adulthood.  And while correlation itself does not prove causation, there may very well still be at least somewhat of a causal link all the same that cannot be readily explained away, particularly for those who begin any significant drinking before age 15.  That said, the specious conclusion that New Zealand and Australia somehow should raise their drinking ages any higher than 18 is unwarranted and not actually supported by the data in this study.

Take it from us in the USA, who have had a legal drinking age of 21 since the 1980s (and much earlier than that in some states).   It simply does NOT work, and merely forces drinking further underground and makes it far more dangerous than it has to be.   It infantilizes young people and erodes respect for the law, and overall does more harm than good.  So what should be done to reduce and/or delay youth drinking, assuming that is the goal?

• Raise the taxes on all alcoholic beverages across the board, ideally making such levies proportional to alcohol content.  That is the single most effective and cost-effective way to reduce alcohol-related harms without actually violating anyone's rights.  So raise them as high as you possibly can without triggering widespread moonshining and bootlegging.
• Set a minimum price floor for alcoholic beverages as well, for both on and off-premise sales.  Both this as well as raising alcohol taxes would have a larger impact on young people since they are more price-sensitive on average.
• Reduce alcohol outlet density in places where such outlet density is very high.
• Restrict or ban alcohol advertising, especially ads aimed at young people.
• Crack down on drunk driving, drunk violence, drunk vandalism, and drunk and disorderly conduct--for ALL ages.  Hold individuals accountable for their behavior, no matter how wasted they are.  Period.
• Increase alcohol education and treatment programs.  Yesterday.  And include social norms marketing in this broadly-defined education program.
• And last but not least, before they even consider raising the drinking age, how about actually enforcing the 18 drinking age they have now?  Seriously.  And by that, we mean targeting vendors with complicance checks, rather than the young people themselves.

And there you have it.  There are far better alternatives than raising the legal drinking age.  And raising the drinking age can actually work at cross-purposes with the alternatives discussed above.  True, delaying the onset of youth drinking--especially regular drinking--can evidently be beneficial to a point.  But when you make the perfect the enemy of the good, you ultimately end up with neither.

Latest New Zealand Study Reeks of Junk Science

A recent study has come out that supposedly shows a long-term increase in "serious traffic crashes" among 18-19 year olds in New Zealand following the lowering of their drinking age from 20 to 18 in 1999.  Previous studies found only a short-term effect, if even any effect at all.  But upon closer inspection, there is far less here than meets the eye.

First and foremost, the maxim that correlation does not prove causation holds true for any observational study of this nature, especially with such relatively modest "effect sizes".  Secondly, the study used 20-24 year olds as the comparison group, and we at Twenty-One Debunked have repeatedly noted how doing so is problematic in light of Dee and Evans (2001), Asch and Levy (1987 and 1990), and Males (1986), who found that raising the drinking age to 21 merely redistributed (i.e. delayed) some traffic deaths from 18-20 year olds to 21-24 year olds after controlling for a host of other variables.  There is no reason to believe that the reverse couldn't happen when drinking ages are lowered.  Thirdly, the study in question did not actually show an absolute increase in traffic crashes among 18-19 year olds, only a relative "increase" relative to 20-24 year olds as both decreased dramatically but decreased faster for the latter group.  Finally, the study found no evidence of a "trickle-down" or spillover effect on 14-17 year olds despite the fact that NZ doesn't even have a hard drinking age, but rather just a purchase age of 18 with rather shoddy enforcement.  Though since 2013, the loophole that allowed furnishing to minors was partially closed among other changes, but the study does not include any data beyond 2010.

Furthermore, another recent study casts further doubt on the claim that lowering the drinking age led to any sort of "parade of horrors" that the pro-21 crowd likes to claim occurred as a cautionary tale.  Put simply, lowering the drinking age was not a disaster after all, nor would it likely be the case if done in the USA.

So consider this latest claim debunked.  Old enough to go to war = old enough to go to the bar.  'Nuff said.

Lowering NZ Drinking Age to 18 Not a Disaster After All

According to a new study, it turns out that New Zealand's lowering of the drinking age from 20 to 18 in 1999 had essentially no impact on the drinking behaviors of young people, contrary to what some people have claimed.  By studying a combination of survey data, hospital admissions, and road crashes, researchers found little to no change for 15-19 year olds relative to 22-23 year olds between 1996 and 2007.  Although there was a short-term spike in alcohol-related hospital admissions (involving a small number of individuals) immediately after the law change, the overall impact of the law change was found to be minimal.  Food for thought.

This was not the only study that found little to no effect of the drinking age change.  Last year, when NZ was debating whether or not to raise the drinking age (which they ended up keeping at 18), another study came to a similar conclusion about the drinking behaviors of young people.  And contrary to what the fearmongers have been claiming, teen drinking has actually declined in recent years.  So it looks like the wowsers were wrong, at least about the drinking age.  But don't expect MADD and their ilk to agree with these studies.

Victory in New Zealand

Last night, the New Zealand Parliament apparently listened to reason and voted to keep the drinking age unchanged at 18.  This is the second time since 2006 that any attempt to raise the drinking age over there has failed.  While the rest of the Alcohol Reform Bill is still being hammered out, we can thankfully rest assured that the NZ drinking age will remain 18 for the foreseeable future.  As a result, we at Twenty-One Debunked hereby honor all of those who voted to keep it 18, especially Nikki Kaye (National) and all of the Greens.
 
To be honest, we at Twenty-One Debunked were a bit worried that New Zealand would actually go through with raising the drinking age to 20, and in doing so ruin any chances that we in the USA could lower our drinking age to 18.   After all, a good 3/4 of the adult population in NZ supported raising the drinking age to 20 or even 21, which is roughly the same percentage over here that favors keeping the American drinking age at 21.  That is, 18-20 year olds are an outvoted minority who would have been subject to tyranny of the majority had it been up to a popular vote alone.  But that's precisely why all modern democracies, even relatively direct ones like Switzerland and several US states, still have legislatures to make laws (and courts to interpret them) rather than literally put everything up to a popular vote.  Remember, what is popular is not always right, and what is right is not always popular.  Albert Einsten knew that quite well.

And it's not like raising the drinking age would have actually done much good.  Next time someone claims that lowering the drinking age to 18 in 1999 created a "crisis" in problematic drinking among teens and young adults that wasn't there before, be sure to show them this link to set them straight. Long story short: from 1996/1997 to 2006/2007 it did not significantly increase among 15-24 year olds, but did increase among people over 25. But I guess it's easier to scapegoat young people for adult problems rather than actually try to solve them.  Fortunately, the NZ Parliament was smart enough to see through the lies and do the right thing, at least as far as the drinking age is concerned.

As for the rest of the Alcohol Reform Bill still being debated, we at Twenty-One Debunked generally support those provisions, even though they may be rather weak.  There is still no definite provision for minimum pricing of alcohol, which according to international evidence would likely have had the largest impact on New Zealand's legendary drinking problem.  But some provisions, such as giving communities more say over alcohol outlets and reducing trading hours (currently 24/7), are clearly a step in the right direction.  Ultimately, New Zealand's drinking culture needs to change, and Parliament needs to step up to the plate and pass sensible laws that encourage that to happen, but without violating the civil rights of any individual or demographic group.  But will they have the intestinal fortitude to do so?

Listen Up, Kiwis--Keep It 18

New Zealand will vote on whether or not to raise the drinking age to 20 sometime in the next week or two.  It will be a conscience vote rather than a bloc vote, so there is no reason to vote along party lines.  We at Twenty-One Debunked have the following things to say to the New Zealand Parliament:

Take it from us in the USA, where the drinking age has been 21 since the 1980s.  We can honestly tell you that raising the drinking age does NOT and will NOT work. All it does is force drinking underground and make it more dangerous than it has to be. Just go to any American college campus and you will see that the emperor isn't wearing any clothes. Ditto for high school keggers.

Next time someone claims that lowering the drinking age to 18 in 1999 created a "crisis" in problematic drinking among teens and young adults that wasn't there before, be sure to show them this link to set them straight.  Long story short:  from 1996/1997 to 2006/2007 it did not significantly increase among 15-24 year olds, but did increase among people over 25.  But I guess it's easier to scapegoat young people for adult problems rather than actually try to solve them.

Listen, if NZ really wants to tackle its legendary drinking problem, which affects ALL ages and not just young people, it would be best to raise the alcohol taxes, set a price floor, reduce alcohol outlet density and advertising, crack down hard on drunk driving/violence/disorderly conduct, and increase alcohol education and treatment.   You may also want to lower the BAC limit for drunk driving to 0.05 to match Australia as well.  But leave the drinking age alone, and actually enforce it better and close the loopholes.   Keep the drinking age 18, but require ID from anyone who looks under 30, and require TWO forms of ID for anyone who looks under 18, period. Crack down hard on those who buy for minors, and stores that sell to minors (or don't check ID).  And close the loophole that allows furnishing to minors under 18 other than one's own children. 

Also, the split age proposal is still problematic because allowing 18-19 year olds to buy alcohol only in bars and not off-premise in stores would encourage drunk driving among that age group, particularly in rural areas with inferior public transport infrastructure and taxis that cost an arm and a leg.  (Remember, this is not Sweden we're talking about.)  If you want to reduce the availability to those under 18 from older friends and strangers, simply enforce the existing laws better and close the furnishing loopholes, full stop.  Alternatively, you could consider putting a cap on the amount of alcohol that an 18-19 year old can purchase at the store in the same day (i.e. no kegs/cases/large liquor bottles, and no more than one off-premise transaction of any kind per day) to discourage purchasing for minors (and high school keggers) while still allowing 18-19 year olds the ability to buy alcohol for personal use legally.

Most importantly, a cultural change is desperately needed in New Zealand across the board as far as alcohol is concerned.  Take a look at other countries with a drinking age of 18 or even lower, especially southern Europe.  You can learn a lot from them.  They generally do not fetishize alcohol by treating it as a major rite of passage. They treat it as a neutral substance that can be good or bad depending on how it’s used, and all drinkers are held to the same high standards of conduct regardless of age. Alcohol-related misbehavior is seen as a conscious choice, and (unlike in predominantly Anglo-Celtic cultures like NZ) alcohol is never accepted as an excuse for doing anything that would be considered unacceptable when sober. As a result, overindulgence and lager-lout behavior is decidedly “uncool” over there, rather than glamorized like it is NZ and other Anglo-Celtic countries.  Remember that every attempt to create a culture of abstinence has failed miserably (six o'clock swill, anyone?), so it's best to aim for a culture of moderation instead.  It's what Aristotle would have wanted. 

Finally, if you feel that that 18-20 year olds are not mature enough to be trusted with a beer, how can you possibly trust them with a gun, voting, raising kids, or any of the other numerous rights and responsibilities of adulthood? If you're old enough to go to war, you're old enough to go to the bar. 'Nuff said.

New Zealand Revisited

(NOTE:  This blog is from a primarily American perspective)

It's official.  New Zealand has a drinking problem.  While America does too, if you scrape the bottom of the barrel you will actually find quite a few countries that are worse than the good old USA in terms of dangerous and excessive drinking, and NZ appears to be one of them.  And it appears to be getting worse over there as time goes on.

New Zealand has always had such a problem to some extent.  Google "six-o-clock swill" and you'll quickly see that it goes back at least a century.  But the recent increase can be traced back to 1989, when the Sale of Liquor Act dramatically liberalized the booze laws.  Trading hours for booze became 24/6 (still no Sunday sales), up from the previous 10 pm closing times, and the looser licensing laws caused number of outlets to more than double from 1989 to 2009.  Booze prices also shrank relative to average incomes, and "loss leading" became a common practice.  In 1999, on the same day the drinking age was lowered from 20 to 18, they began allowing beer to be sold in supermarkets, accelerating the rise in outlet density, and with the simultaneous addition of Sunday sales, it was now 24/7.  All this in a country that is generally soft on crime and tolerant of extreme drinking and drunken violence.

The Law Commission has apparently come up with a few recommendations to tackle the problem.   In their report, they include the following, among others:

• Have a "one-way door" (no entry) policy for pubs and nightclubs after 2am
• Require all pubs to close by 4am
• No off-premise sales after 10pm
• Restrict "irresponsible" promotions that encourage excessive drinking
• Raise the alcohol excise tax by 50%
• Raise the drinking age from 18 to 20

While we at Twenty-One Debunked would not have a problem with the first five changes being implemented, we clearly take exception to the last one, raising the drinking age.  We do not think it will do any good, and may possibly throw gasoline on the fire.  Clearly, NZ doesn't have a teen drinking problem, they have a Kiwi drinking problem, one that spans all ages.  Plenty of 20-29 year olds can't handle their liquor, should the drinking age be 30 then?  Funny all the vitriol about raising the tax, often the same people over 20 who want the drinking age raised.  If the proposed 50% tax hike (really a mere 10% price hike) bothers you, you're clearly drinking way too much.  Perhaps you should cut down.  Chivas Regal said it best.

Besides, raising the age limit would be a major victory for the pro-21 crowd in this country as well if the drinking age was raised, reducing the chances that our drinking age will be lowered any time in the near future.  It would only reinforce the specious claim that lowering the drinking age in America would be a disaster, since it would seem that NZ tried it and couldn't handle it.  Nevermind that NZ is a very different culture from the USA, and that other factors were at work--neoprohibitionists apparently can't be bothered with pesky facts.

Instead, we propose the following for NZ in addition to the Law Commissions recommendations (aside from the drinking age), and these will likely work in other countries with a serious drinking problem:

• Set a price floor for alcohol, especially at off-licenses, and ban the practice of "loss leading" (selling below cost).
• Restrict or ban alcohol advertising, especially on TV and radio.
• Increase the penalties for drunk driving, and step up enforcement.
• Lower the general blood alcohol limit for driving to 0.05, and the under-20 limit to 0.02 or less (the limits are currently 0.08 and 0.03, respectively).
• Hold parents accountable for what their under-18 kids do, especially if the parents supplied them with alcohol beforehand. 
• Put more cops on the street, and get tough on real crime, especially drunk violence.
• Ban drinking in the street by all ages, or allow very limited designated areas to do so.
• Restrict the number and density of alcohol outlets, especially in cities.
• Increase alcohol education and public awareness campaigns.
• Exempt microbreweries from any new tax hikes (they are generally not part of the problem, and they would have the hardest time absorbing such price increases). Otherwise, tax the hell out of alcohol, especially RTDs (alcopops).
• Do NOT raise the drinking age! Just enforce it better, especially for off-premise sales, and close the existing loopholes on furnishing alcohol to minors under 18 (which the Law Commission also recommends).

Note that some of these things are a bit stricter than that which we would propose for America.  However, NZ has a worse drinking problem than we do, and appear to be one of the worst in the world.  Only Russia and a few other former Soviet-bloc countries appear to be worse, and not by all that much. 

Interestingly, the New Zealand Medical Association agreed in 2006 that the drinking age should remain 18, since there was no clinical evidence that alcohol was more harmful to an 18 year old than a 20 year old. But they did say that the current drinking age needs to be enforced better, and also called for tighter advertising restrictions on alcohol.  Unfortunately, they appear to have flip-flopped on the drinking age issue this time around.

What exactly were the effects of lowering the drinking age from 20 to 18 in December 1999?  It turns out that those who claim it was a disaster haven't the foggiest idea of cause and effect.  Carnage on the highways?  Unlikely to be causal.  According to the International Traffic Safety Data and Analysis Group, the reporting of nonfatal injury crashes by police had improved since 2001. Teen traffic fatalities fluctuated a great deal due to their small numbers, but the rates generally remained below their 1999 values from 2000-2008.  Increase in youth crime and violence?  That had been rising since 1992, seven years before the drinking age was lowered, and actually declined around 1998-2002 before resuming its upward trend.  Again, unlikely causation.


(Take a look at our May 2009 blog post about New Zealand for more information about the issue of their drinking age)

In other news, NZ's driving age (currently 15) was raised to 16 effective in mid-2011, and it will also be a bit tougher to get a license.  To that, we say good--if any age limit should be raised over there, the driving age is it.  Kiwis tend to have higher fatality rates compared to Aussies or us Yanks, and their driving age is ridiculously low compared to most other countries.  They are already debating whether to raise it further to 17.  But while they're at it, why not get tougher on drunk driving and reckless driving for all ages?

The Truth About New Zealand

New Zealand. An island country of 4.3 million people in the southwest Pacific, 1250 miles from Australia. With more sheep than people, they say. What could this tiny, halfway-around-the-world country possibly have to do with the American drinking age debate? Everything, at least according to the pro-21 crowd.

It turns out that New Zealand was the only country in the past decade that has lowered its drinking age, and it did so from 20 to 18 in December 1999. With disastrous results, according to the pro-21 crowd. The same folks that otherwise insist that we can't compare America to other countries with lower drinking ages imply that we would experience disaster as well. Only a few studies have been done to determine the effects of the drinking age change, most notably Kypri et al. (2005) which was co-authored by MADD member Robert Voas from the USA.  When the study came out, leading to news sound bites alleging a dramatic increase in 15-19 year old fatalities resulting from the change, the pro-21 crowd ate it right up without questioning a word of it. But several astute observers did precisely that--they questioned. When the Progressive Party of NZ tried to raise the age back to 20 in 2006 as a result of the moral panic, it fortunately got defeated by a conscience vote after much protest against it. Today in 2009, the drinking age issue is back on the front burner again, in both NZ and the USA. And over here, when the pro-21 crowd is pressed and refuted by those in the movement to lower the drinking age, they like to pull the New Zealand card. And here is where it gets debunked.


Traffic Crashes

The study by Kypri et al. (2005) allegedly found an increase in traffic crashes that involved injuries (not fatalities as is often claimed) among 15-19 year olds since the drinking age was lowered, comparing the four years before to the four years after December 1999. What the media don't mention is that the "increase" was relative to 20-24 year olds, not an absolute increase. There was actually a decrease in all three age groups studied (ages 15-17, 18-19, 20-24), but the 15-19 year old crashes decreased at a slower rate than 20-24 year olds. The original claim that an additional 12 deaths per year resulted from lowering the drinking age was left out of the final paper, probably for good reason. The study also does not control for potential confounders (other than the population of each age group), and we know that such confounders existed during the study period (e.g. increased outlet density, falling alcohol prices, increasingly aggressive advertising/marketing, rise of alcopops). And yes, it is possible for different age groups to be differentially affected by things other than the drinking age, especially the last three things. So one could not really tease out the effect of the law change. The authors assume that teen crashes would have probably dropped even more had the age not been lowered, but that assumption is far from obvious.  Also, according to the International Traffic Safety Data and Analysis Group, the reporting of nonfatal injury crashes by police had improved since 2001.  Teen fatalities fluctuated a great deal due to their small numbers, but the rates generally remained below their 1999 values from 2000-2008.

Indeed, using 20-24 year olds as a control group is a poor choice. We know that several American studies found that drinking age changes merely shift deaths from one age group to another (see Five Studies that Debunk the Rest for more info), so that could be a reason for the faster decline among 20-24 year olds when those who were 18-19 when the age was lowered turned 20 in 2001-2002. Also, Brownsfield et al. (2003) found that college students already over 20 when the age was lowered drank less immediately after the age-lowering than immediately before. That could be due to not wanting to go to the bar as much due to the resulting influx of younger people, or simply because it would be more crowded. Or they may have felt that their thunder was stolen, so to speak. This (drinking less and staying home more) could also plausibly lead to fewer crashes among those 20 and over. A better choice would have been to use 25-29 year olds as a control group as they would be distant enough to not be affected by the drinking age, but still close enough to be "in the loop" of the latest social trends.

What about the apparent spillover effect on 15-17 year olds, you ask? Interestingly, the "increase" in crashes was even higher for them than for 18-19 year olds, and females were affected more than males in both groups. In America, this would make no sense since crashes involving female drivers are less likely to involve alcohol, and the same is true for 16-17 year olds. So other factors had to be involved. And there is a much more plausible explanation as well.

A little background about New Zealand is necessary to understand all this. First of all, they never really had a true drinking age like we do in America, just a purchase age (we will use the term "drinking age" anyway). They also allow moonshining and drinking in the street. When the age limit was 20, it was poorly enforced, and there were numerous exceptions to the law as well. IDs were not consistently checked, if at all. Back then, it was fairly easy even for 15 and 16 year olds to get into bars and be served. Nod nod wink wink, as long as you behaved yourself we'll let you drink. When the age limit was lowered to 18, however, they really cracked down on bars and restaurants who served to anyone under the new drinking age, but for off-licenses (liquor stores, supermarkets, convenience stores) the enforcement was just as lax as before, which was very lax indeed. Youth under 18 ironically found it harder to get into bars when the age was lowered. So those 15-17 year olds who could no longer go to bars simply went to the stores instead. What they couldn't buy themselves they often got strangers outside to buy for them (furnishing to minors was and remains effectively legal, unless it can be proven who bought it, but even then the penalty is modest). Premixed spirit-based drinks (ready-to-drink, or RTDs), like our alcopops only stronger, were often the drink of choice, as well as cheap liquor. And the already low prices were effectively falling due to the practice of "loss leading," to the point where one could easily get completely wasted for only a few dollars, as RTDs were cheaper than soda or even water. And wasted they got, without the moderating influence of the pub and with little incentive to behave. 

The seeds appear to have been planted in 1989, a full ten years before the drinking age change.  That was the year the Sale of Liquor Act was enacted, which liberalized licensing laws and allowed for 24-hour opening hours.  The number of licensed outlets skyrocketed since then.  Also, NZ began to allow the sale of beer in supermarkets, and legalized Sunday sales of alcohol, on the very same day that the drinking age was lowered.  This further increased the number and density of outlets as well as the resulting availability of booze.

The prexisting trend of increasing binge drinking (which was always worse than in America), combined with the converging trends of falling real alcohol prices, increasing outlet density, 24-hour sales, aggressive marketing and advertising, and the rise of alcopops/RTDs, was a powder keg. Non-alcohol factors, such as faster cars and increasing illegal street racing, may have also played a role in the car crashes as well. If the law (and enforcement) change did anything, it was merely a spark, and rather ironically so at that.

Other effects

Alleged effects of the drinking age change were not limited to motor vehicle crashes. Putative increases in binge drinking, alcohol overdoses, unsafe sex, teen pregnancy, and violent crime have all allegedly been linked to the age-lowering by those who seek to raise the drinking age, using mostly anecdotal evidence. But most of these were either continuations of preexisting secular trends and/or things that could also be explained by other factors (falling alcohol prices relative to income, increasing outlet density, 24-hour sales, aggressive marketing and advertising, and the rise of alcopops/RTDs). These variables are seldom controlled for in the studies. For crime, there were changes in how some crimes were reported and collated since the age was lowered as well, further muddying the waters. Also, many of these effects (such as higher pregnancy rates) were also found for those over 20 as well, and there is a strong correlation between the behavior of adults and that of teens. Indeed, the alleged "effect sizes" of some of these things, though practically small in most cases, are implausibly large given the minimal enforcement of the previous drinking age, and so such effects are likely spurious. The same can be said about the alleged effects on traffic crashes.

Contrary to popular opinion, there was little evidence that 18-19 year olds were a significant source of alcohol for younger teens. But the number one source of alcohol, as it had always been, was parents. Parents were, and still are, the elephant in the room than no one wants to talk about. A pink elephant in this case. Not only do they drink quite a bit themselves, they would also buy large quantities of beer, RTDs, and liquor for 15 year olds, and those 15 year olds would often share it with their younger friends as well. Often unsupervised, in God knows where. Remember that 15 is the driving age in NZ. That means the parents essentially handed them whiskey and car keys. Have fun, don't kill nobody! Look, you simply can't legislate common sense, and raising the drinking age back to 20 would do nothing for this issue.

What to do about it


New Zealand has always had a drinking problem worse than America. There is much debate on what to do about it. But raising the drinking age would likely be fighting fire with gasoline. It would at best be a distraction from the worst drinkers of all--20-29 year olds. Here is what we, the TSAP, recommend instead:

• Raise the tax on all alcoholic beverages, especially RTDs, hard liquor, and cheap beer.
• Set a price floor for alcohol, especially at off-licenses, and ban the practice of "loss leading".
• Restrict alcohol advertising, especially on TV.
• Increase the penalties for drunk driving, and step up enforcement.
• Lower the general blood alcohol limit for driving to 0.05, and the under-20 limit to 0.02 or less (the limits are currently 0.08 and 0.03, respectively).
• Hold parents more accountable for what their kids (under 18) do, especially if the parents supplied them with alcohol beforehand. Duh!
• Put more cops on the street, and get tough on real crime, including drunk violence.  Penalties and enforcement for violent crimes appear to be far too lax in New Zealand.
• Ban drinking in the street by all ages, or allow very limited designated areas to do so.
• Restrict the number and density of alcohol outlets.
• End 24-hour bar-hopping and have a pub closing time of 2 am, and/or a one-way door policy after 1 am. That's evidently when the crazies come out, and the crazy stuff happens.
• Increase alcohol education and public awareness campaigns.
• Do NOT touch the drinking age!  Just enforce it better at off-licenses to increase compliance, and close the existing loopholes on furnishing alcohol to minors. 

These common-sense measures would work wonders, and would affect all ages. Which is exactly what a lot of adults who would rather scapegoat teenagers don't want. Those who insist on raising the drinking age in NZ are so fixated on age that they fail to see the forest for the trees. Gee, who does that sound like? If they are really that concerned about age, than raising the driving age (currently 15) to 16 or 17 is probably the best place to start (along with making the road test harder).

Interestingly, the New Zealand Medical Association agreed in 2006 that the drinking age should remain 18, since there was no clinical evidence that alcohol was more harmful to an 18 year old than a 20 year old.  But they did say that the current drinking age needs to be enforced better, and also called for tighter advertising restrictions on alcohol.

Relevance to America, or Lack Thereof

It goes without saying that while America is not Europe, we are not New Zealand either. As mentioned before, there are several significant differences between the two countries that the pro-21 crowd likes to gloss over. And even there, the effects of the drinking age are likely spurious. So consider this one debunked as well.

QED