Although there is no established nationwide sex-while-driving (SWD) standard offense, engaging in sexual activity while behind the wheel violates reckless driving laws as well as state indecent exposure laws.
Although often discussed as a humorous subject, SWD can be deadly.
Two jurisdictions have specifically designated it as a crime: the city of Detroit has banned it; and the State of Washington categorizes such “embraces” as a specific reckless driving offense. (see Section 46.61.665 of the Washington Code).
In a recent study, 32.8% of men responding and 9.3% of female respondents admitted engaging in SWD.
Sexual activity lasted less than 10 minutes for most respondents and half were traveling 61–80 mph during sex. 1.8% nearly had a crash (none actually had a crash).
A passenger may be arrested for indecent exposure or public lewdness (or committing a lewd act), but the driver will bear the brunt of charges and be subject to the greater penalty -- reckless driving.