Crucially, the federal law does not allow for "grandfathering" (exempting those who were already 18) nor does it provide exemptions for active-duty military personnel, a departure from some previous state-level policies. Retailers are now required to verify the photo identification of anyone under the age of 30 attempting to purchase these products. Rationale for the Change

The T21 law, signed as part of a massive federal spending bill, amended the Federal Food, Drug, and Cosmetic Act to make it unlawful for any retailer to sell tobacco products—including e-cigarettes, e-liquids, and pods—to anyone under 21 years of age. Unlike many federal laws that include a phase-in period, this mandate became effective immediately upon signing.

The legal age to purchase Juul products and all other forms of tobacco and nicotine underwent a historic transformation in the United States on December 20, 2019. On this date, the federal government officially raised the minimum legal sales age from 18 to 21 through the "Tobacco 21" (T21) legislation. This policy was a direct response to the "youth vaping epidemic," a surge in nicotine use among middle and high school students that many public health experts attributed to the rise of sleek, high-nicotine devices like Juul. The Federal Mandate: "Tobacco 21"

The push for a higher age limit was rooted in two primary scientific and social arguments: Where are kids getting JUUL? - Truth Initiative