What we all now call “a bottle of wine” may soon differ from what it has been for decades, and that could create confusion for how wine buyers will someday purchase wine.

No changes will occur immediately, but there may be an impact on wine buyers soon. The changes being contemplated may alter savvy wine consumers’ buying habits and confuse the unwary.

It all started decades ago when the U.S. government decided that “a bottle of wine” legally should be described as having 750 milliliters of liquid.

Before that, a standard bottle was called a fifth — 20% of a gallon. This measure came so close in ounces (25.6) to the number in 750 ml (25.4 ounces) that the government accepted the latter size as its standard “bottle” size.

At the time, the government created regulations intended to standardize all alcoholic beverage bottle sizes as a way of codifying what could be sold to consumers. These “standards of fill” regulations for wine were:

—187 ml (the so-called split).

—375 ml (a half-bottle).

—750 ml (a bottle).

—1.5 liters (a magnum).

No other sizes were permitted; later, other sizes were added, like the 500 ml bottle (in 1990).

Standardization here seemed appropriate to some people here, even though many other countries had no such requirements. However, for the most part other countries followed the U.S. regulations, especially if they wanted to sell their products here.

Now a recent proposal by the agency that regulates alcoholic beverages (Tax and Trade Bureau, TTB) would do away with all standardized sizes in favor of a no-rules approach in which any size is permissible… as long as the package clearly states how much is inside.

After decades during which 750 milliliters was the de facto standard, the government’s new proposal, if approved, could create confusion. But those who want to see this change approved argue that it finally would bring the United States into conformance with the rest of the world.

Why, ask those who favor the change, should 762 milliliters be illegal? Or 543 ml? Or any size?

My concern here is that as time goes by, chicanery could ensue and consumers risk nefarious behavior by some unscrupulous bottlers. Such a change would put a burden on consumers and even on some wineries.

I spoke with John Hinman, a San Francisco beverage law attorney, about this. He favors the TTB change, pointing out that the proposal arose because many wine companies are now packaging wines in 250-milliliters cans, which is not yet a legal size. A federal regulation change would permit that size package.

What problems do consumers potentially face? For one thing, diners in restaurants could become confused. Imagine the scenario:

You order a bottle of a wine and it arrives at your table in the white-gloved hands of a tuxedo-clad server who compliments you on your fabulous taste.

At that moment, it becomes essential for you to check to see if it contains 750 milliliters. If instead it has say, 700 milliliters, then you would end up paying 7% more for the wine than under the present system.

Wineries are required to identify the amount of the contents on the label. But I’ve seen many labels without the required amount on the label. In such cases, what recourse is there for the consumer?

(And we have all seen this in action: the required alcohol statement is printed in black on black labels.)

Also, in some states where consumers can buy wine only in state stores (i.e., Pennsylvania), buyers can’t look at the label to determine the contents until they order a bottle of it from a clerk.

I don’t suspect that wineries will try to take advantage of the new regulation if it is approved. But wiping out the entire “standards of fill” regulation just to permit the 250-ml can of wine to exist seems like performing open-heart surgery with a switchblade. We’ve had the scalpel for decades.

Why not just allow the 250-milliliter size to be legal and leave the other regulations to remain?

Wine of the Week: 2018 Dry Creek Chenin Blanc, Clarksburg ($16): Rarely has there been a more reliable white wine than this one, not to mention a classic, a great value, and a wine of impeccable taste. The only reason someone would demean it might be because it has the barest hint of residual sugar (0.4%). This wine is blessed with more floral aromas than most I have tasted, and it performs its profession most admirably by bringing the flavors together in all sorts of Asian cuisines and other foods with assorted flavors. It comes from the rich soils of the Stockton Delta, perhaps the greatest place in America to grow Chenin, and it is destined to be even better in a year – at least for those people will understand how it will develop a trace of honey in time. Almost always available at about $13, and some discounters have it even cheaper. Not to be missed.

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Dan Berger lives in Sonoma County, where he publishes “Vintage Experiences,” a subscription-only wine newsletter. Write to him at winenut@gmail.com. He is also co-host of California Wine Country with Steve Jaxon on KSRO Radio, 1350 AM.