LATCH

LATCH, standing for Lower Anchors and Tethers for Children, is the United States standard for securing child safety seats to dedicated metal anchorages built into the vehicle rather than routing the adult seat belt through the seat. Mandated in new passenger vehicles and child seats sold in the US from September 2002, it is the American counterpart to the ISOFIX system used in Europe and much of the rest of the world, and it was introduced to tackle the same well-documented problem: the high rate of installation errors that left belt-fitted child seats dangerously loose or incorrectly routed.

The system has two structural elements implied by its name. The lower anchors are two steel bars fixed in the vehicle's rear seat bight, the gap where the seat cushion meets the backrest, to which flexible or rigid connectors on the child seat attach. The top tether is a strap that runs from the upper rear of a forward-facing child seat to a dedicated anchor point behind the seat, in the parcel shelf, seat back or boot floor. Together these establish a secure attachment without any reliance on the seat belt.

The top tether performs a specific and important job. In a frontal crash, a forward-facing seat held only at its base tends to rotate forward, pitching the child's head downward and forward; the tether resists this rotation and can reduce head excursion by a significant margin. For this reason LATCH guidance treats the tether as essential for forward-facing installations, even where a seat is alternatively belted in.

The overarching aim of LATCH is to make correct installation simpler and more error-resistant. Clipping standardised connectors onto fixed anchors removes much of the judgement and tensioning skill that belt installation demands, and clear attachment confirmation helps caregivers know the seat is properly secured. In practice the standard has measurably improved the proportion of seats installed tightly and correctly, though real-world misuse has not been eliminated.

There are practical caveats that distinguish LATCH from its ISOFIX cousin. US guidance imposes a combined weight limit, commonly around 29.5 kilograms or 65 pounds including the seat, above which caregivers must switch to seat-belt installation, and lower anchors are generally not approved for use in centre positions unless the manufacturer specifies anchor spacing. Although LATCH and ISOFIX share design intent and a similar 280-millimetre anchor spacing, they are not officially interchangeable. It relates closely to integrated child seats and to child-security door locks as part of a vehicle's provision for younger passengers.