Steve Portigal pointed me on this jpost article about a kosher telephone "that minimizes Shabbat desecration" for military soldiers in the israelian army.So first, look at the problem from the user point of view:

"Until now, every telephone call [on Shabbat] that was not a matter of life and death or close to it raised questions and deliberations among religious soldiers regarding halachic permissibility. Now the calls can be made without any qualms,"

And then, solutions:

Dialing and other electronic operations on the "Shabbat phone" are performed in an indirect way so that the person using the phone is not directly closing electrical circuits. Instead, an electronic eye scans the phone buttons every two seconds. If a button has been pressed, the eye activates the phone's dialing system. This indirect way of activation is called a grama. (...) the Shabbat phone was just one of several devices that helps minimize Shabbat desecration. "The IDF is already using electric gate and door openers based on grama technology," he said. "And pilot versions of proximity sensors, magnetic cards and electronic eyes have been created." (...) Another gadget that is now widely used in the IDF is a self-erasing pen. Writing is one of hundreds of activities prohibited on Shabbat. However, writing in ink that does not remain legible is a less severe transgression that is permitted when necessary, even if there is no danger to life.

Why do I blog this? because design is about constraints and it's very intriguing to see how technological artifacts can be designed with those constraints in mind. I am always amazed by the workarounds for constraints that we don't experience in our usage of the same technology. Yet, as in Jan Chipchase talk at LIFT07 about illiterate users, this I about delegation. In that case, the delegation is done to the machine and not another human. This topic is also close to what Bruno Latour describes about how we humans delegate morals to objects (see his safety belt example).