Yevamos, Chapter 12, Mishnah 1. This chapter deals with the details and fine points of the chalitzah ceremony, and our Mishnah opens with two topics: the composition of the beis din before which the chalitzah is performed, and the type of shoe used for chalitzah.
The composition of the beis din:
"Mitzvas chalitzah bishloshah dayanim, va'afilu sheloshtan hedyotos" - the chalitzah must be performed before three judges, even if they are not experts but ordinary Jews who have not received semichah. This does not refer to the semichah given in our times, but to the original semichah transmitted from the generation of Moshe Rabbeinu.
Why did the Mishnah use the term "judges"? The Gemara explains that a minimal level of knowledge is required of them: they must be able to read out to the yavam and the yevamah the verses that these two must recite during the chalitzah ceremony.
The Gemara further explains that although three are required, two more are added to them, five in all, in order to publicize the chalitzah. The two additional men are not part of the beis din and need not know how to read, and the beis din is valid even without them; they are simply joined to the proceedings for the sake of publicity.
Which shoe is used for chalitzah:
The difference between a min'al and a sandal lies in the material from which they are made:
Min'al - made of soft leather.
Sandal - made of hard leather.
The sandal is the shoe that should preferably be used. The reason: since the min'al is made of soft leather, it may be torn and fail to cover most of the foot - in which case it is invalid - yet because of its softness it still sits on the foot, and a person might mistakenly use it. The sandal, by contrast, is made of hard leather, and when it is cracked or broken it cannot be used at all. For this reason a sandal is preferred, since with it no mistake is possible: it is not fit for use unless it covers most of the foot.
The details of the shoe and of the chalitzah in the Mishnah:
"Chaltzah b'min'al - chalitzato kesheirah" - this is not the preferred way, since ideally a sandal should be used, but after the fact the chalitzah is valid.
"B'anpilya - chalitzatah pesulah" - a foot covering made of cloth, of wool, or of a type of felt is not valid; the shoe must be made of leather.
"Sandal sheyeish lo akeiv - kasher, v'she'ein lo akeiv - pasul" - a sandal that has a covering enclosing the heel is valid; but if it has no covering at all and is merely a flat surface without a heel, it is invalid.
"Min ha'arkuvah ul'matah - chalitzatah kesheirah; min ha'arkuvah ul'ma'alah - chalitzatah pesulah" - if the shoe is tied from the knee and below, and it is removed from there, the chalitzah is valid. But if it is tied only above the knee and not below it, the chalitzah is invalid. The shoe must be wrapped or tied below the knee, and be removed from there.
In summary: in this Mishnah we learned that chalitzah is performed before three judges, even ordinary men, provided that they can read out the verses, and two more are joined to them for the sake of publicity. We also clarified the type of shoe: ideally a sandal of hard leather, and after the fact even a min'al; an anpilya of cloth is invalid; a heel is required; and the chalitzah must be performed from the knee and below.
As the chapter continues, we will go on to discuss the remaining details and fine points of the chalitzah ceremony.