By Isaac
California is putting teenagers as old as 15 through a state-mandated seat-belt fit test—and those who fail it will have to remain in a child restraint such as a booster seat.
The new rule takes effect January 1, 2027. It applies to children ages 8 through 15, meaning it reaches right up to a teenager’s 16th birthday.
The law stops short of ordering every 15-year-old into a booster. Teenagers who pass all five steps may use an adult belt, while those who miss even one step will need a child restraint.
The story exploded across social media Saturday as Californians compared Sacramento’s latest mandate with the state’s much larger public crises.
That is the real political problem for Sacramento. Even Californians who support car-seat safety can see why a near-driving-age teenager in a booster seat sounds like government micromanagement run wild.
California’s official legislative record shows that Democratic Gov. Gavin Newsom approved Assembly Bill 435 on October 7, 2025. The measure was filed as Chapter 434 and becomes operative on January 1, 2027.
The law rewrites what California considers “properly restrained by a safety belt.” For children who are at least 8 but younger than 16, buckling the belt will not be enough unless the child also passes every part of the five-step test.
If the child does not pass, the statute requires an “appropriate child passenger restraint system” meeting federal standards. In practice, for an older child who has outgrown a harnessed car seat, that generally means a belt-positioning booster.