Halakhah su Deuteronomio 25:2

In general, anyone designated by the Halachah as a rasha (sinner) cannot serve as a witness (Shemot 23:1). Thus, anyone who commits a sin punishable by malkot (lashes) cannot serve as a witness (as the Torah refers to one who is punished by malkot as a rasha, in Devarim 25:2). Similarly, deliberately violating a Torah law that is punishable by kareit or death disqualifies one as a witness. In addition, one who engages in theft or other monetary offenses and one who does not believe in the thirteen basic beliefs of Judaism cannot serve as witnesses. Nonetheless, the Gemara (Sanhedrin 26b) recounts:

And Ramban, may his memory be blessed, does not hold of this approach and he does not lean towards it; but [rather] he holds that there always be an explicit warning about the one to be lashed or about the one being killed - and not from a general negative commandment. And even if Scripture makes his death penalty explicit a hundred times, the Rabbi will still say that it does not punish unless it warns (and not from a general negative commandment). And he does not consider a general negative commandment as a warning in the place of lashes, because of that which is a famous law in our hands, "We do not administer lashes for a general negative commandment." And therefore he, may his memory be blessed, said that they already clarified in the Gemara from which verse we learned to administer lashes to the rebellious son: And they said in Sanhedrin 71b, "It is like Rabbi Abahu, as Rabbi Abahu said, 'We learned lashes for one who puts out a bad name, as it is written about him (Deuteronomy 22:18), "and they shall chasten him," from "and they chastised him" (Deuteronomy 21:18) that is written about the rebellious son; and "son" from "son" [in] "And if the evildoer be a son of (liable for) lashing" (Deuteronomy 25:2).'" And there is also a difficulty for Rambam, may his memory be blessed, in this, [since] he writes in the second root, that we do not give lashes by the power of a comparison (which is what seems to be indicated here). And he also challenged the Rabbi about his statement that the rebellious son is liable for the death penalty for his indulging in much eating and he did not distinguish between the first eating and the second. But they said explicitly in the Gemara in Sanhedrin 71 that we do not punish the first eating of the rebellious son with the death penalty, but rather lashes, as they said, "We warn him in front of two [witnesses] and we lash him in front of three. [If] he goes back and goes bad, he is judged by twenty-three [judges for the death penalty]." He, may his memory be blessed, also wrote and this is his language, "And what is fit to take out from this is that the first eating is prevented (forbidden) and its punishment is lashes, and the punishment of the second is death, and they are two preventions (negative commandments) in the tally of commandments, and they are [both] included in 'You shall not eat upon the blood.'" To here [are his words].

That He prohibited the judge from striking the sinner with great lethal strikes. And the explanation of this is that the limit on all those who are liable for lashes is surely that he is lashed forty minus one, as it appears in the tradition; such that he not strike a person until he assesses the man that will be struck, according to his strength, his years, his condition and the form of his body. If he can withstand the entire striking of the punishment, he is struck [accordingly]. But if not, he is struck according to the measure of what he can withstand - [though] not less than three lashes, [based on] His saying, "according to his wickedness in number" (Deuteronomy 25:2). And the prohibition comes about adding - even one lash beyond the judge's assessment of what he can withstand - to his striking. And that is His saying, "according to his wickedness in number. Forty is he to strike him, he may not add" (Deuteronomy 25:2-3). And the language of the Sifrei (Sifrei Devarim 286:10) is, "If he does add, he transgresses a negative commandment. I only know of his adding to the forty. From where [do we know the same for his going beyond] each and every assessment that the court assessed? Hence we learn to say, 'he may not add, lest he add.'" And from this prohibition is [derived] the prohibition to strike any Israelite - if we are prohibited from striking the sinner, all the more so do we not strike any [other] person. And He already prohibited us from hinting as if one will strike, even if he does not strike. They said (Sanhedrin 58b), "Anyone who raises his hand against his fellow is called, an evildoer - as it is stated (Exodus 2:13), 'and he said to the evildoer, "Why would you strike your fellow."'" (See Parashat Shoftim; Mishneh Torah, The Sanhedrin and the Penalties within their Jurisdiction 16.)