Is It Illegal to Use an Expired Car Seat?

What Federal Law Actually Regulates

Federal Motor Vehicle Safety Standard No. 213 (FMVSS 213), codified at 49 CFR § 571.213 and administered by the National Highway Traffic Safety Administration (NHTSA), sets the minimum performance requirements a new child restraint system must pass before it can be sold: a 30 mph frontal sled test using instrumented dummies that measure head, neck, and chest forces, plus permanent labeling requirements naming the manufacturer, model, and month and year of manufacture.^[1] That standard governs manufacturing and the first sale of the product. It does not say anything about how long a private owner is allowed to keep using the seat afterward.

NHTSA has addressed the expiration question directly, and its answer is narrower than most parents assume. In a formal interpretation letter, the agency’s Office of Chief Counsel confirmed that the federal requirement to manufacture and sell compliant equipment does not reach the resale — or, by the same logic, the continued private use — of a used child restraint once a consumer has purchased it in good faith.^[2] The federal “make inoperative” provision at 49 U.S.C. § 30122, which bars disabling a certified safety feature, is written to reach manufacturers, distributors, dealers, and repair businesses — not a parent strapping their own child into a seat they already own.^[2]

There is also no federal requirement that a manufacturer print an expiration date on a car seat at all. The practice is voluntary, driven by each manufacturer’s own engineering judgment about how long its specific plastics and hardware remain safe — which is exactly why NHTSA tells consumers to fall back on a flat six-year rule whenever a seat carries no printed date: replace it six years from the date of manufacture regardless.^[3] Put together, these two facts explain the paradox at the center of this topic: the federal government built the crash-test standard and encourages the expiration practice, but it left the job of actually enforcing that expiration date to the states.

The Legal Bridge: How “Manufacturer’s Instructions” Becomes Enforceable

State legislatures did not need to write the word “expired” into their vehicle codes to reach this issue, and rewriting a statute every time engineering guidance changes would be impractical. Instead, most state child-restraint statutes use a single recurring phrase: the seat must be installed and used according to the manufacturer’s instructions. Ohio’s statute, for example, requires every restraint to be used “in accordance with the manufacturer’s instructions.”^[8] Texas requires a child to be “secured … in accordance with the instructions of the manufacturer of the safety seat system.”^[10] Tennessee’s statute repeats the same clause across every age category it covers.^[7]

A car seat’s instruction manual is not a suggestion once that clause exists — it becomes the actual legal text the driver is being measured against. A manufacturer’s manual that states, in its own printed language, “do not use this child restraint after [month/year]” is functionally identical, from an enforcement standpoint, to any other line in that manual: routing the harness through the correct slot, using the top tether, or matching the seat to the child’s weight. Cross any one of those lines, including the expiration date, and the seat is no longer being used “according to the manufacturer’s instructions” — which is the exact language the citation gets written against.

In practice, an officer rarely pulls a car seat out of a vehicle during a routine stop just to check the manufacture-date stamp molded into the plastic. Citations more commonly follow when a seat looks visibly outdated, damaged, or mismatched to the child’s size during a stop made for another reason, or when the seat gets inspected as part of a crash investigation. The date-stamp violation is real and enforceable everywhere the “manufacturer’s instructions” clause exists in the statute — it is simply a lower-frequency trigger for enforcement than the civil exposure described later in this report.

Why the Expiration Date Exists: A Six-to-Ten-Year Materials Problem

An expiration date is not a marketing device to force a repeat purchase — it is a materials-engineering deadline. The load-bearing shell of a modern car seat is molded from polypropylene, a plastic chosen because it flexes and absorbs energy well when new. A parked car’s interior swings from below freezing overnight to well past 130°F in direct summer sun, and that swing repeats every single day the seat sits in the vehicle. Each cycle makes the plastic microscopically expand and then contract, and over several years those repeated movements open microscopic stress fractures inside the shell that are invisible during an ordinary glance-over.

Ultraviolet light compounds the same problem from a different direction: even through tinted glass, UV exposure gradually breaks down the polymer’s internal chemical bonds, turning a shell that was once pliable into one that is measurably more rigid and brittle. In a real collision, a brittle shell is the opposite of what the seat is designed to do — instead of flexing to absorb the crash’s kinetic energy, it can shatter on impact and transfer that force directly to the child instead of around them.

The harness webbing and internal foam degrade on the same multi-year clock through an entirely different mechanism: daily friction, tension from being buckled and unbuckled thousands of times, spilled liquids, and repeated cleaning with household chemicals slowly reduce the tensile strength of the woven straps and the energy-absorbing capacity of the foam lining. Metal hardware — the buckle release and harness adjusters — can also accumulate rust and debris to the point of jamming or releasing prematurely under crash loads. Because none of this damage shows up in a casual visual check, manufacturers set a fixed replacement window rather than asking parents to inspect for degradation they cannot actually see.^[13]

A second, unrelated reason compounds the first: crash-test science keeps moving. Since testing began in 1971, every car seat sold in the United States was required to pass only a frontal-impact sled test — not a side-impact test, even though side, or “T-bone,” collisions are disproportionately severe because there is little to no crumple zone between the striking vehicle and the child. Congress ordered NHTSA to close that gap in the 2012 MAP-21 transportation law; the agency proposed rules in 2014 and finalized the new standard, FMVSS 213a, in 2022, with full manufacturer compliance now required by December 5, 2026 after an 18-month extension from an original mid-2025 deadline.^[4] An independent analysis of NHTSA crash data covering 2015–2019 found that side impacts accounted for roughly a quarter of the annual deaths among children riding in car seats, even though every seat on the market at the time had only ever been tested against a frontal crash.^[6] Once FMVSS 213a takes full effect, seats manufactured under the older, frontal-only standard will still be legal to keep using until they expire on their own schedule — but a seat that was never tested against a side impact simply cannot offer protection its newer replacement is now required to prove.^[5]

The Bigger Exposure: Civil Liability, Not the Citation

A $25 to $75 traffic fine is not what makes this issue worth taking seriously, but the civil-liability picture is more state-specific than a simple negligence per se argument, and in at least two of the states surveyed here it runs in the opposite direction from what might be expected. Negligence per se — the principle that violating a safety statute can itself establish negligence when the violation causes the exact kind of harm the statute was written to prevent — is a real doctrine in many states.^[14] But Ohio and Pennsylvania each have a statute that goes the other way: Ohio’s child-restraint law expressly states that a parent’s failure to secure a child properly is not admissible as evidencein a civil case brought on the child’s behalf against another allegedly liable party, and Pennsylvania’s child-restraint violation similarly cannot be used as evidence in any civil action or treated as contributory negligence. In those two states specifically, an expired-seat citation should not reduce an injured child’s own recovery against the driver who caused the crash. Other states may allow the seat’s condition to be raised through a separate causation or comparative-fault theory, but that requires state-specific legal authority this report does not have for every jurisdiction.

Separately from that fault-allocation question, an expired seat’s condition can still become a factual issue in how a specific injury is explained medically — for example, whether a seat’s degraded shell contributed to the severity of an injury as a matter of causation, distinct from whether the parent was at fault for using it. Picture a driver rear-ended at a stoplight by another car that ran the light, with a child riding in a seat manufactured nine years earlier, three years past its printed expiration date; if the plastic shell fractures along the harness path instead of flexing to absorb the impact, that failure mode can become a contested medical-causation issue in the resulting injury claim, separate from who is legally at fault for the crash itself.

This liability question sits alongside other equipment-failure scenarios covered elsewhere on this site — see our companion research on whether you can sue for faulty airbags for how the same chain-of-causation analysis applies to another piece of federally regulated occupant-safety equipment, and our guide to seatbelt law for how restraint-use statutes function for adult passengers.

Checking Whether a Seat Has Expired

Every car seat sold in the United States carries a permanent label — molded into the plastic shell or printed on an affixed sticker — stating the model name, the manufacturer, and the exact month and year of manufacture, as required under FMVSS 213’s labeling rules.^[1] Many manufacturers print the expiration date directly next to that manufacture date; others state the seat’s useful life (commonly six to ten years) in the printed owner’s manual instead of on the shell itself. If neither the label nor the manual states an expiration date, NHTSA’s default guidance is to replace the seat six years after its date of manufacture.^[3]

A seat that has been in even a moderate crash should be treated the same way as an expired one regardless of what the date stamp says, because the same invisible micro-fracturing described above can happen instantly in a collision rather than gradually over years. Anyone transporting a child in a hand-me-down or secondhand seat should also confirm it has never been the subject of an active NHTSA recall before relying on it — a separate question our companion research on selling car seats covers in more detail, since recalled seats carry an absolute federal sale ban that does not depend on the expiration date at all.