The latest study of Tobacco 21 laws shows they were a resounding....DUD in terms or reducing young adult smoking, vaping, or smokeless tobacco use rates in the USA. Being published in a famously anti-tobacco journal, Tobacco Control, the authors of course wanted to put a positive spin on it though nonetheless, as shown below (emphasis ours):
Results Although we did not find evidence that state T21 laws were associated with cigarette, smokeless tobacco or ENDS [i.e. vapes] use overall, the federal T21 law was associated with lower use of all three tobacco products by 0.39–0.92 percentage points. State flavour restrictions were associated with lower use of cigarettes by 0.68 (−1.27 to –0.09) and ENDS by 0.56 (−1.11 to –0.00) percentage points, but not with smokeless tobacco. A three-way interaction revealed that state and federal T21 laws together were associated with a lower prevalence of ENDS use among 18–20 years, but there were no differences in cigarette use from both policies combined versus either alone.
Conclusion State and federal T21 laws are broadly effective at reducing adult tobacco use, while state flavour restrictions specifically lower use of cigarettes and ENDS.
Got that? The state level laws were useless, period, but the federal Tobacco 21 law passed in December 2019 was somehow "broadly effective" because it appeared to trivially reduce tobacco/nicotine product use by not even a full percentage point. Never mind that that latter was not enforced until well into 2020, enforcement still remained spotty for a while, and that its passage coincided with two major confounds: 1) the EVALI (vaping illness) outbreak that, while clearly due to adulterated black market THC vape products, was fearmongered by the mainstream media to include all vape products, and 2) the COVID-19 pandemic that, for better or worse, seemed to discourage smoking and encourage quitting, since many people feared that smoking made them more vulnerable to the virus. But no, it HAD to be due to the Tobacco 21 law, because reasons. Or something.
Even flavor restrictions were more effective than Tobacco 21 laws!
So how many IQ points did YOU lose from the mental gymnastics of reading all for the above quoted article abstract beyond the stuff in bold? The study was behind a paywall of course, so we couldn't delve further into it, granted. But even a cursory reading of the abstract shows that the Tobacco 21 laws are a joke, and not a very funny one at that. And worse, it may have even driven some young vapers (back) to smoking, which would clearly be a net public health loss. But try convincing the zealots of that!
These unimpressive findings dovetail nicely with other studies as well. As for whether raising the tobacco/nicotine age limit from 18 to 21 reduces the use of such products among people under 18, the evidence for that is very weak and mixed at best.
As for the few previous studies that did appear to find statistically and practically significant effects from the Tobacco 21 laws, those apparent results are most likely a result of short-term effects as well as an artifact of confounders like cigarette tax hikes.
(Cigarette tax hikes, which mean higher prices, are in fact one of the most effective and cost-effective ways to reduce smoking at the population level, though they still have their limits of course. And while they may be classist, at least they are not ageist, and they don't blatantly violate anyone's civil rights.)
Regardless, even if Tobacco 21 laws were ever proven to be effective, Twenty-One Debunked would still oppose them on principle, as we believe that in a free society worthy of the name, civil rights inherently supersedes "public health". That is true in regards to tobacco, alcohol, cannabis, or anything else.
(Mic drop)
UPDATE: A few older studies have found modest but significant decreases in retail tobacco sales following the raising of the smoking age to 21 in early adopter states like California and Hawaii. And another study found no change in overall ever or current smoking among California 18-20 year olds, but did find a modest decrease in daily smoking among that age group relative to 21-23 year olds (whose daily smoking actually increased three years later) in the same state. This of course echoes Miron and Tetelbaum (2009) as well as Asch and Levy (1987 and 1990), Males (1986), and Dee and Evans (2001) in regards to the 21 drinking age. That is, endogeneity, early-adopter effects, short-term effects, and seesaw/delay effects all appear to be at play here. The supposed miracle turned out to be a mirage all along, in other words. Thus, especially in light of the most recent study discussed in this article, there were really no benefits that cannot be alternatively achieved with higher cigarette taxes and/or better enforcement of the previous 18 age limit, and if anything the 21 age limit appears to be counterproductive in the long run.
UPDATE 2: Even the CDC's very own 2022 study found mixed and ambiguous effects of Tobacco 21 laws, and such effects sometimes even appeared to differ by race as well (in favor of whites, with null or even perverse effects on young people of color). Oops!
UPDATE 3: Another recent study found that while self-reported teen smoking and vaping rates declined after Tobacco 21 laws, biomarker exposure showed mixed evidence at best, implying that fewer young smokers are identifying as smokers (and similar findings for vaping). Thus, the supposed reductions in smoking and vaping in surveys and sales data are at least largely an artifact of underreporting and cross-border shopping rather than real reductions. Oops!