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What exemptions or medical exceptions exist for California's booster seat law in 2025?
Executive summary
California’s current baseline law requires children under 8 years old or shorter than 4 feet 9 inches to use a child restraint or booster and generally to ride in the back seat; the state also recognizes limited exceptions for medical reasons and other constrained situations [1] [2]. In 2027 a revised approach—AB 435—replaces some age rules with a five‑step belt‑fit test for ages 8–16, meaning a child who fails the test must use a booster; the bill and existing code both note narrow medical and vehicle‑configuration exceptions [3] [4] [5].
1. What the law says now — age, height and the back‑seat rule
Current California law requires children to be secured in a child passenger restraint system (car seat/booster) until they turn 8 or reach 4'9", and safety guidance from state agencies recommends children under 13 sit in the back; several overviews and legal summaries repeat this baseline [1] [6] [7].
2. Medical and other statutory exceptions that appear in reporting
Reporting and local agency pages identify narrow exceptions: medical reasons that make standard restraints impractical, emergency situations, vehicles without rear seats, or when the restraint cannot be properly installed in the rear seat (examples collected by sheriff and safety sources) [8] [2]. Legal guides and county policy pages explicitly state “medical reasons” or “medical conditions” as recognized exceptions to normal placement or restraint requirements [9] [10].
3. What AB 435 changes — the five‑step fit test and how that affects boosters
Assembly Bill 435 (filed by Lori Wilson) changes the practical test for whether a child can use an adult seat belt: commencing January 1, 2027, the law defines “properly restrained” for ages 8–16 by a five‑step checklist (sitting back against the seat, knees bending at the seat edge, shoulder belt across chest/collarbone not neck, lap belt low on thighs/hips, and ability to remain seated for the trip); if the child fails any step, the statute requires a booster to achieve correct belt fit [3] [4] [5].
4. How the law treats medical exceptions under AB 435
AB 435’s text and legislative summaries focus on belt fit as the determinant and continue to operate within the existing framework that recognizes medical exceptions elsewhere in vehicle‑code provisions; legislative and local summaries show medical reasons still permit different arrangements, though the bill’s public explanations emphasize use of the fit test and boosters when fit is inadequate [3] [4] [8]. Available sources do not provide model language giving a new, expanded medical‑exemption process distinct from prior law — they report only that medical reasons remain an exception [4] [8].
5. Practical situations often cited as “exceptions” by local guides
County and law‑firm guides list a handful of operational exceptions that make front‑seat riding or alternative placement lawful: no rear seat, rear seats occupied by other children under certain ages, seats that are side‑facing or cannot accept a restraint, or a pediatrician’s written note for medical necessity — these appear repeatedly in local guidance and legal explainers [10] [8] [11].
6. Penalties, enforcement and fairness context
Media reporting about AB 435 notes enforcement would use the five‑step test as the standard for whether a child is “properly restrained”; some outlets reported proposed fines (e.g., low civil citations under earlier bill drafts) while others focused on public education and group endorsements (CHP, AAA, pediatric groups) promoting the test to reduce injuries to smaller children [5] [1] [12]. The bill’s proponents framed the change as size‑based safety rather than age‑based restriction [13].
7. Disagreements, hidden agendas and limits in coverage
Safety advocates (AAA, CHP, AAP) are prominently cited in favor of the five‑step approach as evidence‑based; opponents in legislative debate raised practical concerns — for example about pickup‑truck cabs and rural families — and some lawmakers pushed back on age‑based front‑seat bans [12] [14]. Coverage varies: some outlets emphasize confusion and clarify that the law is size/fit focused rather than a blanket rule forcing teenagers into boosters [15] [13]. Available sources do not include the final regulatory guidance or a consolidated state FAQ explaining step‑by‑step how medical exemptions will be documented or adjudicated by police.
8. What parents should do now (based on reporting)
Until enforcement guidance is published, parents should follow the five‑step belt‑fit test described in AB 435 and keep children in boosters when belts don’t fit properly; if a child cannot safely be restrained because of a medical condition, sources point to seeking written documentation from a medical provider and to consult local sheriff/CHP guidance about lawful exceptions [3] [10] [8].
Limitations: this summary uses reporting, bill text excerpts and agency summaries in the provided set; if you want the exact statutory text for AB 435 or the Vehicle Code sections on medical exemptions, request the specific bill PDF or Vehicle Code sections and I will cite them from the sources you provide [4] [3].