1) SENTENCED BUT NOT KILLED (Yerushalmi Halachah 4 Daf 3a)
משנה אין העדים הזוממים נהרגין עד שיוגמר הדין שהרי הצדוקים אומרים עד שייהרג שנאמר נפש (תחת) [ב]נפש
(a) (Mishnah): False witnesses are only killed if the accused murderer had been sentenced (but not killed); in contrast to the Tzedukim (Sadducees) who said that they are only killed if the accused murderer had been killed, as they understood it from the pasuk (Devarim 19:21) - 'a soul for a soul'.
אמרו להן חכמים והלא כבר נאמר ועשיתם לו כאשר זמם לעשות לאחיו והרי אחיו קיים
(b) (Chachamim to the Tzedukim): But the pasuk already said (pasuk 19), "And you shall do to him as he intended to do to his brother" - meaning that his brother is still alive!
אם כן למה נאמר נפש (תחת) [ב]נפש יכול משקיבלו עדותן ייהרגו ת"ל נפש תחת נפש הא אינן נהרגין עד שיוגמר הדין:
1. If so, why did the pasuk say 'a soul for a soul'? I might have thought that as soon as their testimony was accepted (even before the verdict, if they were found to be false) they can be killed; the pasuk teaches from 'a soul for a soul' that they are only killed after the verdict was made.
גמרא א"ר זעירה הדא אמרה עד זומם אינו נפסל בבית דין אלא מעצמו הוא נפסל פתר לה בהתרייה [אחת]
(c) (Gemara - R. Zeira): From the Beraisa that follows, it is clear that a witness found to be false by Beis Din is not only disqualified as a witness from the time that he was found to be false onwards, but rather, it also applies retroactively back until the time that he originally gave the testimony. R. Zeira explained that the (upcoming) Beraisa refers to when they testified about two different things at the same time.
ותני כן אמר רבי יוסי במה דברים אמורים בשתי כיתי עדיות ובשתי התריות אבל בעדות אחת ובהתרייה אחת כל עדות שבטלה מקצתה בטלה כולה.
(d) (Beraisa - R. Yosi): (If two witnesses testified that a person stole (an animal) and they also testified that he slaughtered it - if they were proved to be false about the theft, (since part of their testimony has been cancelled) their entire testimony is cancelled and the witnesses must pay double (as the punishment for the theft), but the accused is exempt for the extra payment for the slaughtering, since there is no longer testimony that he stole it.) When is it said (that the accused pays double, as the original testimony is not cancelled)? When they testified separately about the theft and the slaughtering; but if both testimonies were given at the same time, once part of the testimony is cancelled, the entire testimony is cancelled.
מהו כל עדות שבטלה מקצתה בטלה כולה היו עומדין ומעידין עליו בעשרה בניסן שגנב את השור באחד בניסן וטבח ומכר (בחמשה)[בעשרה] בניסן והוזמו (באחד)[בחמשה] עשר בניסן כל עדות שהעידו (מב')[מי'] בניסן עד חמשה עשר בניסן למפרע הרי אלו פסולין.
(e) What is the meaning of 'if part of the testimony is cancelled, the entire testimony is cancelled'? On the 10th of Nisan they testified that the person stole an ox on the 1st of Nisan and that day (10th), he sold or slaughtered it. If they were then found to be false on the 15th of Nisan, all testimony that they gave from the 10th to the 15th is retroactively disqualified.
א"ר בא בר ממל תיפתר במעידין עליו בכרך אחד ולית שמע מינה כלום
(f) Rejection (R. Ba bar Mamal): (It could be that a false witness is disqualified from the point of discovery onwards, but here) R. Yosi was discussing when there was one testimony, so the testimony is fully cancelled at the same time - for example, when the theft and slaughtering were done at the same time; therefore, they are viewed as one occurrence and when part of it was proved false (such as the slaughtering) the entire testimony is disqualified. If so, this case is not a proof that a false witness is disqualified retroactively.
ותני כן היו (מן)[הן] הראשונים והן האחרונים הוזמו בראשונה אין בכך כלום בשנייה הרי הוא לו עדות אחת בשלישית הרי היא לו כשתי עדיות.
1. Support (Beraisa): When a pair of witnesses testified that Ploni was in possession of a field for three years and a second pair came and declared their testimony of the first year to be false, the entire testimony is now cancelled (as the beginning of the possession has been disproved). If they disproved the testimony of (only) the second year (so that the first pair are no longer believed even for the third year), all that remains is the testimony of the first year. If they disproved (only) the third year, the testimony of the first two years remains.
2. What is the case (of this Beraisa that we do not say that since the testimony of all three years came at the same time, as soon as the third year was disproven, the entire testimony falls)?
)אמר)[אם] במעידין עליו בכרך אחד לית שמע מינה כלום
3. If they testified as one group, we have already discussed that their entire testimony would be cancelled.
לא אתייא אלא על ידי עדיות סגין
4. Rather, it must be referring to when there was more than testimony - therefore, when the testimony of the second or third year was disproven, the testimony of the other years remain intact.
)אמר ר' זעירא הדא אמרה עד זומם אינו נפסל בבית דין אלא מעצמו הוא נפסל(:
(g) (Note: This sentence is removed by the Tosefos Rid.)