1) THE DEGREE OF DISQUALIFICATION OF A SHTAR WITH THE WRONG PLACEMENT OF THE WITNESSES
OPINIONS: The Mishnah states that there are two types of Shtar: "Pashut" ("straight") and "Mekushar" ("tied"). A Shtar Pashut is supposed to have the signature of the witnesses on the face of the document, while a Shtar Mekushar is supposed to have their signatures on the back of the document. The Mishnah states that if the signatures appear in the wrong place, the Shtar is Pasul. Does this mean that the Shtar may not be used for anything at all, or that the Shtar is valid but it is not as powerful as an ordinary Shtar?
(a) The RASHBAM (DH Shneihem) writes that if a Shtar Chov (a loan document) was written in this manner, it may not be used to collect from fields of the borrower which were collateralized to the loan. The Rashbam's wording implies that he maintains that the Shtar still may be used as proof for the loan. Similarly, the Gemara later (162b) says that if the signatures of the witnesses are distanced two lines from the body of the document, the Shtar is Pasul. RABEINU YONAH there explains that the Shtar still has the power to prevent the defendant from saying that the transaction never happened.
This is difficult to understand. The Mishnah says that the Shtar is Pasul. This implies that it is entirely invalid. The KOVETZ SHI'URIM (#587) explains that a Shtar serves two distinct purposes. The Shtar has the legal powers of a Shtar, and it has the status of Edus, testimony. The Rashbam apparently maintains that although the legal powers of the Shtar are nullified, the testimony still is recorded correctly. The "Edus" aspect of the Shtar therefore remains valid.
(b) The Kovetz Shi'urim quotes the YAD RAMAH (see CHIDUSEHI HA'RAMBAN to the Mishnah here) who apparently argues with this concept. The Yad Ramah says that a Shtar Mekushar should not be considered even Edus, since the witnesses did not clearly sign on what is written in the document (since they signed on the back of the document). The only reason why a Shtar Mekushar is accepted by Beis Din is that the Chachamim enacted that it is a valid Shtar. Since the Chachamim said that this Shtar is invalid, it has no Halachic validity at all and is Pasul. (Y. MONTROSE)
2) THE "KAPDANUS" OF KOHANIM
OPINIONS: The Gemara explains that the reason behind the enactment to use a Get Mekushar was to prevent Kohanim from divorcing their wives hastily. The Gemara attributes their haste to the fact that Kohanim are "Kapdanim" and therefore are easily angered and prone to write Gitin to their wives hastily. Since a Kohen may not remarry his wife once he has divorced her, the Chachamim decreed that a Kohen must write a Get Mekushar if he wants to divorce his wife. A Get Mekushar takes more time to write, and thus the Kohen will have more time to settle down before he divorces his wife.
Why do the Kohanim, the representatives of the Jewish people in the Avodah of the Beis ha'Mikdash, have this particular attribute of "Kapdanus" (see also Kidushin 70b)? This attribute seems to be at odds with their designated role?
(a) The YOSEF DA'AS quotes the YA'AROS DEVASH (Derush 1, p. 24) who explains that inherently the Kohanim are imbued with the attribute of absolute kindness. However, when the Jewish people sinned and caused the Shechinah to distance itself from the nation, the Kohanim's attribute of giving became one of Kapdanus. The Ya'aros Devash writes that this is why the Gemara describes Kohanim as Kapdanim.
This answer is difficult to understand. The Gemara in Yoma (22a, 23a) cites two incidents wherein certain Kohanim acted violently towards other Kohanim during a competition to decide who would do the Avodah in the Beis ha'Mikdash. In one incident, the act of violence actually resulted in a death. These incidents occurred when the Beis ha'Mikdash was standing, and the Gemara implies that the Kohanim were careful about Tum'ah and Taharah in the Beis ha'Mikdash. Why did they act with such violence when the Beis ha'Mikdash stood?
(b) There seems to be a more basic answer. The Gemara often cites a positive trait of the Kohanim: "Kohanim Zerizim Hem" -- "Kohanim are expeditious" (see, for example, Beitzah 18a). The fact that they are both Kapdanim and Zerizim is no coincidence. The Kohanim have an inherent trait, or "Techunah," which can be utilized in a positive way, as demonstrated by the action of Pinchas who saved the Jewish people by killing Kazbi and Zimri (see Bamidbar 25), but which also can be utilized in a negative way, as is apparent from the Gemara in Yoma and the Gemara here. A "Techunah" is in contrast to a "Midah" -- a trait which is not inherent and should be broken if it leads the person to improper conduct.
A similar idea is expressed by the Gemara in Shabbos (156a) which says that a person born under the Mazal of Ma'adim will have a tendency towards violence, but his tendency can manifest itself positively, as a doctor (bloodletter), Mohel, or Shochet, or negatively, as a bandit.
Similarly, RAV AVIGDOR MILLER zt'l said that one reason why Yakov Avinu cursed the anger of Shimon and Levi was to teach them that their trait of Kapdanus and Zerizus was an inherent trait that should be used positively. (Y. MONTROSE)