A door latch mechanism for a vehicle comprising a release lever operable by a door handle and a transmission path linkage containing a resiliently biased inertia device. During normal operation, the inertia device is biased to form a transmission path that transmits an unlatching movement from the release lever to release a latch bolt of the latch. If an impact on the vehicle creates an acceleration force above a predetermined level, the inertia device moves to break the transmission path, preventing the latch from being unlatched.