What you do do with Tefillin - Berakhot 23
To relieve oneself in any manner during prayer would be very disrespectful – there is a natural and healthy human instinct, expressed in most cultures, that considers excrement and urine unclean. So if one manages to excuse oneself and get to a “privy,” or outhouse, what to do with the tefillin? First we can distinguish between an outhouse that has been previously used and a new outhouse – tefillin evidently should not be worn within 4 cubits of excrement, so take them off and put them on again away from a used one. In a brand new outhouse, however, one may take them off at the last minute, do one’s business, and then put them on again at a distance of 4 cubits.
What if you’re going into a used one only to do “Number 1”? Some object that you never know which call of nature will strike once you get started. Others suggest you may hold them in your hand or in your clothes, but then there is the risk that they will fall in (!). But it is made clear that one needs to hold them, for putting them in a hole inside the building leaves them vulnerable to mice, while setting them in a hole outside the building means they could be stolen – one student’s tefillin were stolen by a prostitute who then claimed he had paid her with them, and he was thus shamed into suicide. One of the proposed solutions to this dilemma became an institution in Rabbinic Judaism – to put them in a special tefillin bag when not in use.
The point of this and the remainder of the discussion about what to do with tefillin when eating or sleeping is very simple – tefillin are for prayer; while they need to be protected and respected at other times (thus they may be slept on at one’s head but not at one’s feet), they should not be worn while eating, excreting, or anything in between. This is also why tefillin are not comfortable symbols for secular, cultural or Humanistic Jews to use in their celebrations – while they value and celebrate Jewish culture, some elements of Jewish culture are so clearly attached to a traditional theology and practice foreign to their personal philosophies that philosophy trumps culture. Knowing what something is does not require its use to be an educated Jew.
Rabbi Adam Chalom