For the source text click/tap here: Yevamot 101
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The 12th Perek begins:
If the woman performed the halitzah with a shoe, her halitzah is valid, [but if] with a felt sock נְפִּילְיָא it is invalid. If with a sandal to which a heel is attached it is valid, but [if with one] that has no heel it is invalid. [If the sandal was tied] below the knee the halitzah is valid, but if above the knee it is invalid.
What qualifies as a shoe is not something we often think about--except perhaps on Yom Kippur (and Tisha B'av)--but in the laws of chalitzah, the question carries great importance. Use the wrong type of shoe and the chalitzah is invalid and the widow is unable to marry. The chalitzah shoe must not go above the knee, is to be made of leather with a series of straps that make for easy removal, is to be worn on the right foot, and must have a heel. A wooden shoe would be acceptable (even if not ideal), whereas a slipper would not. A sandal is okay, provided it has a heel.
We explore the cultural meaning behind the sandals and shoes in general and their use in ritual and as a expression of class.