When Germany debates the consequences of cannabis legalization, California is almost always cited as a reference point. The U.S. state opened its cannabis retail shops in January 2018, providing the longest continuous dataset available from any Western market. A new analysis from the University of California, San Diego, has now comprehensively reviewed this entire period, and the results are far less dramatic than either side of the debate would have preferred.
📑 Inhaltsverzeichnis
What the San Diego researchers analyzed
The study was published in the „Journal of Cannabis Research“ by scientists from the Center for Medicinal Cannabis Research and the Herbert Wertheim School of Public Health and Human Longevity Science at UC San Diego. The researchers evaluated responses from 178,836 adults from the California Health Interview Survey, one of the largest regular health surveys in the United States.
The study period spans 2017 through 2024, covering the year before licensed sales began and the first seven years of functioning retail operations. California legalized recreational cannabis in November 2016 through Proposition 64, with the first retail shops opening on January 1, 2018.
Overall consumption barely shifted
The proportion of adults who had consumed cannabis in the preceding year stood at 22.1 percent in 2017 and 23.5 percent in 2024. The authors classify this difference as statistically insignificant. When examining past-month consumption, there was an initial spike from 14.5 percent in 2017 to 17.7 percent in 2018. This figure then declined to 15.4 percent by 2024, a level not significantly different from pre-legalization baseline.
Most noteworthy is what happened in the young adult population: essentially nothing. Among 18- to 25-year-olds, researchers found no significant changes throughout the entire study period. This age group sits at the center of Germany’s legalization debate, with warnings of a consumption surge. The California data does not support such concerns. A similar picture emerged recently from the Trier longitudinal study on consumption following partial legalization, though based on a considerably smaller sample.
Older adults represent the real shift
The genuinely significant change occurred at the other end of the age spectrum. Among 40- to 59-year-olds, monthly consumption rose from 10.7 to 14.5 percent. Among those 75 and older, it more than doubled, from 2.4 to 5.5 percent. The authors attribute this trend to growing interest in health-related applications rather than a new recreational trend among seniors.
This aligns with findings from other countries. A large JAMA analysis of cannabis use among older adults this year showed that many seniors deliberately turn to cannabis to replace conventional medications. Those who frame the legalization debate exclusively as youth protection overlooked the demographic where actual change is occurring. For healthcare planning purposes, this is the more relevant finding.
What this means for the German debate
California is not Germany. The U.S. state operates a fully commercial retail market with advertising and branded products, while German cannabis law permits only home cultivation and non-profit cultivation associations. Nevertheless, California’s trajectory serves as a crucial test case for a central argument. If even a fully commercialized market shows no measurable increase in overall consumption after eight years, the expectation of a consumption boom from Germany’s far more restrictive model becomes difficult to justify.
Conversely, the study offers no blank check either. It measures prevalence—how many people consume cannabis—not how problematic that consumption is. German data such as the 2025 BIÖG drug affinity study do show movement in specific population groups. The honest interim conclusion, therefore, is that major upheavals in either direction have not materialized. Those asking whether cannabis legalization was a mistake find in California evidence primarily of normalization rather than the feared escalation.
Where the study reaches its limits
The authors themselves identify their study’s limitations. The California Health Interview Survey’s methodology changed during the study period, complicating year-to-year comparisons. The pandemic from 2020 onward additionally altered consumption patterns. Furthermore, access to legal cannabis in California is anything but universal. More than half of counties still prohibit commercial cannabis operations. Such local bans are the norm across other U.S. states as well.
What the study does accomplish is a reality check. Eight years is sufficient time to distinguish short-term curiosity effects from lasting behavioral changes. The 2018 spike appears to have been precisely that—a curiosity effect.
Frequently asked questions
Has cannabis consumption in California risen since legalization?
Not to any statistically significant degree. Annual consumption was 22.1 percent of adults in 2017 and 23.5 percent in 2024. The authors classify this difference as insignificant. For monthly consumption, there was a brief spike in 2018 that had normalized by 2024.
Which age group consumes more since legalization?
Primarily older adults. Monthly consumption among 40- to 59-year-olds rose from 10.7 to 14.5 percent, and among those over 75 from 2.4 to 5.5 percent. Researchers suspect growing interest in health-related applications drives this trend. By contrast, consumption among 18- to 25-year-olds remained stable.
How reliable are these results?
The sample of 178,836 respondents is very large and comes from an established state health survey. However, the authors point to methodological changes during the study period, pandemic impacts, and widely varying regional availability. The findings are robust but not directly transferable to other markets one-to-one.
Can these results be applied to Germany?
Only with limitations. California operates a commercial retail market, while Germany relies on home cultivation and non-profit cultivation associations. However, if the far more open California market shows no sustained increase in consumption, there is little reason to expect Germany’s more restrictive model to produce one.
Does the study address problematic consumption?
No. The analysis measures the prevalence of cannabis use, not its intensity or potential harms. Questions about dependence, emergency room visits, or psychological consequences require other research. This study exclusively answers whether more people consumed cannabis after retail shops opened.
Sollte Deutschland sich am kalifornischen Modell orientieren?
Sources: Journal of Cannabis Research (UC San Diego, Center for Medicinal Cannabis Research and Herbert Wertheim School of Public Health and Human Longevity Science), California Health Interview Survey 2017–2024.
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