“Have you had anything to drink tonight?” – a typical question asked by an officer during a routine traffic stop that can transform a speeding ticket into a DUI arrest. An officer can ask you this question even if he or she does not initially suspect you of a DUI. People generally think it is safe to tell the officer they have had “one glass of wine” or “two beers.” Perhaps one glass of wine would be a “safe” answer, if one glass was truly one glass. A recent study at Iowa State and Cornell universities suggests that people generally misjudge the amount of wine they are actually drinking.
According to the National Institute on Alcohol Abuse and Alcoholism, five ounces is a glass of wine. The size, shape and even color of the wine can impact people’s perception of how much wine is consumed. People over poured more often when drinking from a wider glass, pouring white wine as compared to red, pouring with the glass in hand rather than sitting on a table or counter and pouring into a non-empty glass.
Admitting to having consumed any alcohol is a factor a police officer can consider when deciding whether to arrest you for DUI. An admission to drinking alone probably is not enough to support an arrest, but an admission to drinking coupled with other indicia of intoxication, such as bad driving, blood shot watery eyes and slurred speech, might be sufficient. For these reasons, relying on the fact you only had “one glass” of wine when deciding whether you are sober enough to drive, can be dangerous.
Source: https://www.usatoday.com/story/news/nation/2013/09/30/wine-serving-size-too-much/2895661/