Of these, approximately 1,500 were children ages 12 to 17, although the number of visits from this age group increased only slightly over the four years.

For their part, energy-drink manufacturers argue that they are being unfairly targeted. At the Connecticut hearing, the head of public affairs for Red Bull North America, Joseph Luppino, maintained that there is no scientific justification to regulate energy drinks differently than other caffeine-containing beverages such as soda, coffee, and tea—particularly when some coffeehouses serve coffee with a caffeine content exceeding that of a can of Red Bull. “Age-gating is an incredibly powerful tool,” Luppino said, and should be reserved for “inherently dangerous products” like nicotine.

The showdown in Connecticut, which pitted the City Hill students against a growing $55-billion-a-year global industry, was the latest in an ongoing debate about the safety and regulation of energy drinks. In recent years, countries such as the United Kingdom and Norway have considered banning sales to young people, while Lithuania and Latvia have active bans in place. In the United States, along with Connecticut, state legislators in Maryland, Illinois, and Indiana have introduced bills, though none have been signed into law. A South Carolina bill to ban sales to kids under 18—and to fine those caught selling the drinks to minors—advanced through the legislature in April, and is now pending before the state’s full medical-affairs committee. It is supported by the parents of a 16-year-old who died from a caffeine-induced cardiac event after consuming a coffee, a soda, and an energy drink within a period of two hours.

Read: How much caffeine before I end up in the E.R.?

As the regulatory status of energy drinks continues to be debated, a growing number of consumers and public-health advocates are asking why and how a product loaded with caffeine and other stimulants became so popular among young people. The reasons are a mix of lax regulation, the use of caffeine as a sports-performance enhancer among adults, and a bit of scientific uncertainty.

According to the sports cardiologist John Higgins, a professor at McGovern Medical School at UTHealth in Houston, there is also another factor: “very, very intelligent advertising.”

Historically, government agencies such as the U.S. Food and Drug Administration have struggled to regulate beverages with added caffeine. Though it offers some guidance, the FDA allows manufacturers of liquid products to decide on their own whether to market their products as dietary supplements or as conventional foods and beverages, which carry differing regulatory requirements. All three major energy-drink makers now have most of their products regulated as foods rather than dietary supplements—though that wasn’t always the case.