The standard reply I get is something along the lines of "well alcoholism went up" or "drunk driving increased" followed by the also standard "but if we make drugs legal everyone will become druggies and they'll sell drugs to schoolchildren!"
Recently I did get something of a new reply:
Why don’t you ask people who’s lives were wrecked by alcoholism once it became easy to buy all the booze they wanted? ... Grain alcohol is mild compared to serious drugs, especially the manufactured stuff like meth or oxy. I don’t mind being called a drug prohibitionist if you don’t mind being called a drug abuse enabler.
Taking the first (and most common) point first: Alcohol related deaths actually rose during Prohibition, not just from bad booze but also alcohol poisoning as people switched from homebrewed or locally produced beer and wine to hard liquor. It is not widely realized, but during Prohibition the country went from primarily drinking beer and wine to drinking hard liquor. It was a simple matter of economics: if you can smuggle in 500 gallons of something you get more money if it’s whiskey instead of beer so bootleggers brought in (or produced) the hard stuff.
In addition to the increased alcohol related deaths during Prohibition, a large number of deaths were occurring for years after Prohibition ended from the long-term effects of alcohol abuse during Prohibition. So allowing for the lag-time, deaths from drinking done after Prohibition dropped.
Deaths related to alcohol abuse were not the only social cost engendered by Prohibition though. You had the death toll from the gang/turf wars certainly, but you also had the social damage done by the hundreds of thousands of people opposed who Prohibition and continued to drink, becoming scofflaws. This did not merely engender disrespect for the Volstead Act but carried over to law enforcement officers. Cops who had been seen as protectors of society started being viewed as oppressive thugs when they enforced the booze laws, or venal crooks when they didn't. And let's be realistic, there were huge problems with corruption, not just of cops, but of judges and politicians too. Yes, yes, there have always been crooked cops and politicians, but during Prohibition corruption rose to heights not seen since the days of Sodom and Gomorrah.
I do not accept your premise that grain alcohol is mild compared to "serious" drugs. Certainly on a weight for weight basis, but when compared by dose I would argue that grain alcohol is far more damaging to the human body than the vast majority of "serious" drugs. I don't believe there has ever been a single death associated with a marijuana overdose and much of the "ravages" of hard drugs can be attributed to impurities from bad production or from "cutting" the drugs with various substances to improve profits.
I don’t mind being called a drug abuse enabler as long as you answer the question: Please name one problem associated with alcohol prohibition that got worse when it was repealed.
Actually, you know what? I don’t mind being called a drug abuse enabler even if you don’t answer, because with legalization will come better quality control of the drugs, remove toxic production facilities from homes and neighborhoods, reduce the social stigma associated with seeking treatment, and reduce the cost hugely.
I can buy 5 pounds of cut and sifted catnip for under $50, delivered to my door, and once pot is legalized I would be able to do the same with it. And since producing sugar from cane or beets has almost exactly the same economic cost as making cocaine from coca leaves, imagine being able to buy coke from your local Wal*Mart for less than $0.70 per pound.
How many turf wars would be fought with drugs at that price? How many little old ladies would be mugged for their Social Security money if druggies could get their drug of choice that cheaply? How many terrorists could be funded by heroin at $5 a kilo? How much money could the country save by releasing (and never re-incarcerating) the over 50% of non-violent drug offenders currently in the system? Here's a hint - corrections alone cost the country over $70 Billion in 2007. Toss in police and the judicial system and you are up to over $220 Billion. So we're looking at a rough savings of $110 Billion. How many treatment centers could be opened with a tenth of that money? How much safer would our civil liberties be if cops didn’t have to make part of their budget through civil forfeiture, couldn’t stop anyone they chose because they “smelled marijuana”, weren’t executing no-knock raids to keep dealers from flushing evidence?
Hell, how much safer would cops be if they weren’t trying to fight a Low Intensity Combat style war in our inner cities?
So yeah, I’ll see your deaths and social damage by alcohol abuse and raise you hundreds of billions of dollars wasted and millions of lives destroyed by the War on Drugs (and that’s just in the US, let’s not even talk about what the WoD has done to Mexico).