[Volundr]

Pacemakers at least should be a non-issue since the law specifically exempts devices where continuous power is required for the safety of the user. I think an unpowered pacemaker would definitely jeopardize ones safety. But yeah my mind also immediately went to very small devices like hearing aids.

[adrenvi]

Maybe this is why Apple is focusing so much on health sensors. It's a bit of a stretch but it could be argued that Apple's fall detection and heart rate monitoring is required for the safety of the user.