By Joe Sixpack
Posted on January 29, 2010 on Joe Sixpack

THE BEER in front of me was dark and strong . . . and totally illegal in America.

It was an ice bock, an old style that - thanks to one of those puzzling quirks in alcohol law - cannot be brewed in America and sold as beer.

I won't mention the brewer who made it because he could face criminal prosecution. This stems from some basic facts of physical science:

The freezing temperature of water, as any kid will tell you, is 0 degrees Celsius. The freezing temperature of pure ethanol, as Wikipedia told me, is -114 Celsius.

If you submit a batch of, say, double bock to subzero temperatures, the beer's water will freeze before its alcohol does. If you scoop away the ice, you'll be left with a denser liquid of concentrated alcohol and malt.

That's ice bock, and that's illegal, because the process is actually a form of distillation, not conventional brewing. In other words, the final product - in the eyes of the law - is not beer, it's hard liquor.

This hairsplitting is an offshoot of post-Prohibition laws that require distilleries to be separately licensed and their products taxed at a higher rate than beer. Even home brewers are forbidden to make ice bock, lest Uncle Sam's revenuers string 'em up like moonshiners.

You're scratching your head, I know.

What about Molson Ice, Bud Ice and all those other ice beers that were popular back in the '90s?

The feds created a loophole for them, reasoning that only a tiny (or, in bureaucratese, de minimis) amount of water is removed in the final product to produce a beer with about 5 percent alcohol.

By contrast, classic ice bocks lose as much as 50 percent of the water through freeze distillation to reach double-digit alcohol content.

So, what about those famously strong German imports, like Kulmbacher Eisbock and Aventinus Weizen-Eisbock?

They're legit because these arcane distillation regs apply only to domestic beer.

The dirty little secret here is that while American-made ice bocks are illegal, the feds don't bother to enforce the law. A spokesman for the U.S. Treasury's Alcohol and Tobacco Tax and Trade Bureau told me that no one in his office could remember anyone being prosecuted for violating the rule.

So, ice bocks turn up from time to time at festivals or as unadvertised specials at brewpubs. Thick, oily and numbing, they're a complex alcoholic wonder - a challenging variety that nearly every brewer contemplates tackling from time to time.

"No one from the TTB has ever asked me about it," one brewer, who makes a celebrated ice bock every spring, told me mischievously. "If they did, I'd tell them it was a de minimis amount of water removed."

Domestic ice bocks are rarely bottled, however, because that would expose them to federal labeling review. It's one thing to serve an illegal beer on the sly, it's another to dangle the evidence in front of a Treasury agent with an Eliot Ness fixation.

Sadly, these rules and their loopholes have put a dent in America's brewing superiority.

For years, Boston Beer held the record for the world's strongest beer, Samuel Adams Utopias, at 27 percent alcohol. It was a miraculous achievement, a beer that tastes like cognac, costs $150 a bottle and, according to the brewery, is the lawful product of yeast fermentation only.

Late last year, however, America lost its crown when Scotland's BrewDog Brewery released Tactical Nuclear Penguin, an ale described as an "über-imperial stout." Frozen at least three times during production, the beer is an astounding 32 percent alcohol.

The feds aren't taking this sitting down. I'm told that they're considering a rule change that could finally decriminalize ice bock.

"Joe Sixpack" by Don Russell appears weekly in Big Fat Friday. For more on the beer scene in Philly and beyond, visit www.joesixpack.net. Send e-mail to joesixpack@phillynews.com.