A few Gemaras made me wonder when exactly are you allowed to be mishtamash with a mechitza that was made on shabbos and when not? A mechitza made of people can be erected, but why can it be used to be matir? Maybe not tiltul but other things yes?
Chaim Marcus, Springfield, NJ
Dear Chaim,
A mechitza which was made on shabbos, even illegally, Min Hatorah is a valid Mechitza (Eruvin 15a). However, it can be used only when it came about by itself, by a Jew b'Shogeg (he forgot it was Shabbos or didn't know it was forbidden to do) or by a non-Jew for ??himself.
If it was made on purpose (Maizid) then it cannot be used as the Rabbis imposed a Knas (fine). However, one cannot throw from the street into the area enclosed by this mechitza because M'd'Oraisa it really "works".
On Shabbos, a Mechitza can be made of people since there is no semblance of "building", but only if they don't realize they are forming a Mechitza (in order ??not to cheapen Shabbos).
The Rama says this Heter should only be used when in need. (Mishna Brura 362:16-24).
A human Mechitza can also be used to allow a person to return back into his T'chum (2000 Amos). Again, only if they don't know that they are being used as such. (Mishna Brura 405:6-11).
All the best,
Reuven Weiner