734. A Human Wall

Shabbos 16:22

A partition that “just happens” (meaning that it was not erected as a partition but it happens to be a partition) is valid. Similarly, if a partition was erected on Shabbos, it is nevertheless a valid partition. If the partition was erected unintentionally on Shabbos, one may carry within its enclosure on that same Shabbos so long as it is not erected with the knowledge of those who would be using it. If one intends for a partition to be erected on Shabbos, he is not permitted to carry within the area it encloses on that Shabbos even if the one who actually erected it did not intend to violate Shabbos. Similarly, if one erects a partition with actual intention to violate Shabbos, it is prohibited to carry within the area it encloses even if the one who erected the partition did not intend to carry within it.

Shabbos 16:23

A human partition – meaning a wall of people standing next to one another – may be erected on Shabbos so long as those who form this partition are not aware that that’s why they’re standing there. Additionally, the one who wants to use the enclosure formed by the human partition cannot be the one who directs the others to stand there. Rather, a third party should have the people stand there without the knowledge of the one who will doing the carrying.