Physical Dead Man's Switches

Physical dead man's switches have been protecting human lives for over a century. A train engineer's handle that must be continuously held down, a grenade's spoon that flies off when released, a mining machine's emergency stop — these are all physical implementations of the same principle.

The defining characteristic of physical switches is their mechanical simplicity. They operate on direct physical contact: release the handle, and the mechanism activates. There's no software to crash, no server to go offline, no internet connection required.

However, physical switches have significant limitations. They can only trigger a single, predetermined physical action (stop the train, cut power, trigger an alarm). They can't encrypt data, send emails, or make nuanced decisions based on context.

Digital Dead Man's Switches

Digital dead man's switches extend the concept into the information domain. Instead of continuous physical pressure, they may monitor an explicit check-in, account activity, a message response or an application event.

Possible capabilities vary by product:

• Remote check-ins: a user can confirm activity from an internet-connected device • Delayed communication: a service may notify an intended recipient after a missed deadline and warning period • Selected payloads: some services support messages, files or platform-specific data • Encryption choices: designs differ on where encryption happens and who can recover the key • Auditability: well-designed systems expose clear states and allow end-to-end rehearsal

The disadvantages are equally important: servers and email can fail, account activity is not proof of death, recipients may lose access, and a provider can disappear. The action must be judged against the specific product rather than the broad category name.

When to Use Which Type

Use a physical dead man's switch when: • Immediate physical safety is at stake (machinery, vehicles, hazardous environments) • The action must happen in milliseconds • No internet connectivity is available • The trigger mechanism must be tamper-resistant in a physical sense

Use a digital dead man's switch when: • You need to protect information, not physical safety • The action involves delayed information delivery • You need configurable timing with grace periods • You can tolerate internet and provider dependencies • You understand the chosen service's encryption and recovery model

Use both when: • You have both physical safety and information security needs • You want redundancy — a physical switch for immediate danger and a digital switch for long-term information protection

ZeroLatch is an information-delivery service, not a physical safety control. Its shortest check-in is 1 day, lifecycle processing runs daily, and each delivery is intended for one recipient. Do not use it for machinery, lone-worker monitoring, bushwalking rescue or any event requiring immediate action.