Makos 16a.

Some background.

When a husband sends his wife a Get via a shliach he can in theory
(before the shliach hands over the Get to his wife), cancel the
shlichus and the Get is null and void.

A potential problem occurs when the shliach is traveling and is
unaware of the cancellation. He arrives to his destination and gives
the Get to the woman, both being unaware that the Get is worthless!

The woman, being under the impression that she is divorced, goes and remarries and has a child when in reality she is still married to her first husband, leading to a mamzer. Ouch.

In such a scenario Chazal created a rarely-used edict to be used at their discretion known as Hafka’as Kidushin Le’Mafre’a – retroactive anullment of Kiddushin. The basis for this edict goes like this: Since all Jews upon their marriage attest that their marriage is accordance to Jewish law (Kedas Moshe v’Yisroel), one in a sense “conditions” his marriage on the consent of Chazal.

Thus, in the case above (canceling the Get-messenger without notifying him of the canellation), Chazal, seeing the potential problem have ruled that this man and woman were never married. In
other words they retroactively annul their marriage; They were just a man and woman living together.

So this woman (who thought she was divorced) has no halachic issue with her new (and only) husband and their child is not a mamzer.

In Tosfos we find Rabbeinu Shmuel (and other Rishonim) raised many fascinating issues on the above. Firstly, if indeed such is the case then in theory all cases of adultery have a great legal defense; The defendants, man and/or woman, can say that the “hasra’ah’ or warning given to them prior to them sinning was a ‘hasra’as safek’.

How? They can say to Beis Din “how do you know that we are married? True that we may be married now but at some point in the future husband can send wife a Get via a shliach (as described above), then simply cancel the Get and recall the messenger without  advising him, messenger hands Get to wife, causing the marriage to be retroactively nullified and voila! I was never married”.

True it may not happen but it is still a ‘hasra’as safek’!
The second issue raised is even more intriguing. Why do we not utilize this edict and legally reverse the status of all known mamzerim?

How? Have the husband of the woman who had an illicit fair (and had a child from this affair) send her a Get via a shliach, recall but don’t advise the shliach, give over the Get to the adulterers and Presto! The marriage is retroactively nullified and she was never married. We would thus have a world free of mamzerim……

The conclusion of all the Rishonim of why this suggestion would not
work is disarmingly simple.

This edict is enacted only ‘b’dieved’ – when no sin was transgressed,
such as a man changing his mind after the shliach has begun his shlichus and cannot be reached.

Thus, to avoid a potential and unintentional mamzer issue Chazal used their Torah vested power to nullify a marriage.

But to use it to “clean up a mamazer” is something Chazal

surely do not sanction.   And here is the clincher – such a general
ruling would cause “Pritzus” for the fear of illicit affairs that may produce a mamzer would be eliminated.

So for hundreds of years this issue was put to rest. A mamzer status cannot be reversed in this manner.

So here we are in the middle of Ukraine sometime in the late 1800’s.

The famous Rabbi Sholom Shvadron (a Chossid of many Rebbes)
universally accepted for his knowledge and boldness in Halachik
rulings receives a letter from Odessa requesting a ruling on a rather
tragic story.

שו”ת מהרש”ם חלק א – שלום מרדכי בן משה הכהן שוואדרון3 (page 28 of 240) MAHARSHAM’
A distraught Aguna finally receives the unfortunate news that her
husband has died. The Beis Din interrogates the witness and allows her to remarry which she does and is now carrying a child.

Alas! The husband reappears…a case of mistaken identity….
Husband had loaned his passport and the borrower is the deceased. The child to be born will be declared a mamzer.

The Brezhaner Rov, (english) as Reb Sholom Mordechai was called, (Maharsham) comes with a suggestion – only in theory but not in practice as he writes: Have the husband send her a Get etc.… you get the picture. (See above)

see full teshuva here:

שו_ת מהרש_ם חלק א – שלום מרדכי בן משה הכהן שוואדרון3 (page 28 of 240) MAHARSHAM’

As to the ruling of the Rishonim that one should never do it because the ruling was made as a ‘takanah’ and to prevent the creation of a ‘takalah’, argued the Brezhaner Rov, this poor woman is totally innocent. She followed the ruling of the local Beis Din. This case is indeed a ‘takanah’.

Many, rather most, Poskim strongly opposed this suggestion.

Furthermore in this case, as the Maharsham writes, the local beis din had already instructed the poor woman to divorce her first husband, rendering the suggestion moot.

See this link

and other related discussion of retroactive rectification of Mamzeirus here

We discussed the laws of a ‘me’anes’ (rapist) who must marry his victim (with her consent) and is prohibited from ever divorcing her. If he does divorce her then he transgresses a Lo Saa’se and would be chayav Malkus but for the fact that the Torah allows him the opportunity to repent and remarry his wife thus avoiding the Malkus.

The only way he can be Chayev malkus is if he creates a situation which prohibits him from remarrying her. The Gemara attempts to find just such a scenario. Such as if he kills her?  But then he would not be chayav Malkus – he would be subject to much worse.

(shiluach hakan just looks good here).

Reb Akiva Eiger ask as to why not suggest that his wife was a ‘Treifa’, (and would not live 12 months anyway) thus taking her life does not render him chayv misa but nevertheless he must still remarry her…?

The Gemara concludes that the only scenario possible would be if he makes a ‘vow based on the public’s opinion’ (Neder al daas rabim) that he will not have anything to do with this woman who is required to marry. Being that such vows are irrevocable, making such a vow is considered ‘bi’tlo’  – (see end of shiur 3/31/15) he causes the impossibility for him to remarry her and would be indeed chayav Malkus.

We spoke about the Rebbe’s mentioning of this concept regarding the bringing of Moshiach. Tamuz 7549. See here:

ספר השיחות תשמ”ט – חלק ב – שניאורסון, מנחם מנדל, 1902-1994 (page 168 of…