Table 2 Summary of themes

Attitudes toward the safety and acceptability DACU are mixed

Sixty studies (n > 110,289 participants; NR in one study) supported this theme. Participants in 35 studies (n = 67,761), predominantly expressed negative attitudes toward DACU. Participants in 20 studies (n > 23,077, NR in one study) expressed the opposite. Participants in 5 studies (n = 19,451) expressed neutral or mixed views. Subsets of participants in 16 studies (n > 8,039, NR in one study) reported that cannabis can improve or have positive effects on driving ability.

Attitudes toward DACU can differ by age, sex/gender, and cannabis use frequency

Age. Nineteen studies (n = 40,006) supported this theme. Youth were more likely to hold positive attitudes toward DACU than older participants across ten studies (n = 30,603). One study found the reverse (n = 1,773) and eight studies found that older age was unrelated to attitudes (n = 7,630).

Sex/gender. Twenty-six studies (n = 46,694) supported this theme. Men were more likely to hold positive attitudes toward DACU than women across 13 studies (n = 33,376). Two studies reported the reverse (n = 3,416), two reported mixed results (n = 2,842), and nine found no differences by gender (n = 7,060).

Cannabis use frequency. Twenty-four studies (n = 26,637) supported this theme. Frequent users had more positive attitudes toward DACU, reported greater intention to DACU, more frequent past DACU, and lower likelihood of legal consequences than those who used cannabis less frequently across 23 studies (n = 26,378). One study reported no such relationship (n = 259).

Attitudes toward DACU are associated with past DACU and intention to DACU

Twenty-six studies (n = 28,775) supported this theme. Positive attitudes toward DACU were associated with actual DACU and greater intention and willingness to DACU.

DACU is viewed more favorably than driving after drinking alcohol

Thirty-seven studies (n > 56,159, NR in one study) supported this theme. Attitudes toward DACU were more positive than attitudes toward driving after drinking alcohol in 31 studies (n > 49,420, NR in one study). Five studies reported contradictory results (n = 6,672). There was consensus that driving under the combined influence of cannabis and alcohol was riskier than DACU alone across six studies (n = 1,305).

The relationship between legal status of recreational cannabis and attitudes toward DACU is unclear

Fifteen studies (n = 56,127) supported this theme. Opinions toward the DACU safety and related laws differed across five studies (n = 37,477).

Five studies (n = 12,566) did not identify any clear differences. Five studies (n = 6,084) reported various effects of legalization (e.g., anticipated post-legalization rise in DACU prevalence).

Perceived risk of apprehension for DACU is low to moderate

Thirty-one studies (n = 69,503) supported this theme. Perceived risk of apprehension and/or penalty for DACU was low to moderate, especially relative to driving after alcohol, in 25 studies (n = 54,433). One study had contradictory results (n = 416). Fourteen studies discussed the effect of and support for preventive policies, penalties, and detection efforts (n = 26,941).