The Torah maintains the ancient false-witness law but blocks initiating a trial on its basis.
It says a person cannot be tried on one witness’s testimony. Only two or more witnesses can accuse and bring about conviction:
One witness shall not rise up against a man for any iniquity, or for any sin, in any sin that he sinneth; at the mouth of two witnesses, or at the mouth of three witnesses, shall a matter be established. (Deuteronomy 19:15)
לֹא יָקוּם עֵד אֶחָד בְּאִישׁ לְכָל עָוֹן וּלְכָל חַטָּאת בְּכָל חֵטְא אֲשֶׁר יֶחֱטָא. עַל פִּי שְׁנֵי עֵדִים אוֹ עַל פִּי שְׁלֹשָׁה עֵדִים יָקוּם דָּבָר. (דברים י"ט, טו)
The very next verse describes exactly the scenario it just rejected:
If an unrighteous witness rise up against any man to bear perverted witness against him; then both the men, between whom the controversy is, shall stand before the LORD, before the priests and the judges that shall be in those days. And the judges shall inquire diligently; and, behold, if the witness be a false witness, and hath testified falsely against his brother; then shall ye do unto him, as he had purposed to do unto his brother; so shalt thou put away the evil from the midst of thee. And those that remain shall hear, and fear, and shall henceforth commit no more any such evil in the midst of thee. And thine eye shall not pity: life for life, eye for eye, tooth for tooth, hand for hand, foot for foot. (Deuteronomy 19:16–21)
כִּי יָקוּם עֵד חָמָס בְּאִישׁ לַעֲנוֹת בּוֹ סָרָה. וְעָמְדוּ שְׁנֵי הָאֲנָשִׁים אֲשֶׁר לָהֶם הָרִיב לִפְנֵי ה', לִפְנֵי הַכֹּהֲנִים וְהַשֹּׁפְטִים אֲשֶׁר יִהְיוּ בַּיָּמִים הָהֵם. וְדָרְשׁוּ הַשֹּׁפְטִים הֵיטֵב, וְהִנֵּה עֵד שֶׁקֶר הָעֵד, שֶׁקֶר עָנָה בְאָחִיו. וַעֲשִׂיתֶם לוֹ כַּאֲשֶׁר זָמַם לַעֲשׂוֹת לְאָחִיו, וּבִעַרְתָּ הָרָע מִקִּרְבֶּךָ. וְהַנִּשְׁאָרִים – יִשְׁמְעוּ וְיִרָאוּ, וְלֹא יֹסִפוּ לַעֲשׂוֹת עוֹד כַּדָּבָר הָרָע הַזֶּה בְּקִרְבֶּךָ. וְלֹא תָחוֹס עֵינֶךָ: נֶפֶשׁ בְּנֶפֶשׁ, עַיִן בְּעַיִן, שֵׁן בְּשֵׁן, יָד בְּיָד, רֶגֶל בְּרָגֶל. (דברים י"ט, טז-כא)
How can this be?
The Sages call the second case the law of plotting witnesses. In halakhah, if two witnesses testify that someone committed an offense but are shown to have been elsewhere at the time, their testimony is false, and they receive the punishment they plotted for the accused.
In the plain meaning, however, one man accuses another of an offense, rather than plotting witnesses arriving to testify at trial. Accused and accuser stand for judgment to determine who speaks truth: “then both the men, between whom the controversy is, shall stand before the LORD, before the priests and the judges that shall be in those days.” If the judges find a false accusation and testimony, the accuser’s punishment is “as he had purposed to do unto his brother.”
This recalls Hammurabi’s first law:
If a man accuses another of an offense carrying the death penalty and cannot prove his claim, he shall be put to death. (Law 1)
אם איש האשים איש אחר בעבירה הנושאת עונש מוות, ואינו יכול להוכיח את טענתו – הוא יומת. (חוק מספר 1)
In the Torah, however, failure to prove the claim does not suffice for punishment: investigation must establish false testimony.
As noted, the preceding verse prohibits trial on a single witness. Yet the Torah then gives the ancient false-witness law in its original wording because it adopts that law’s principles while limiting implementation at one point.
The passage (Deuteronomy 19:16–21) contains important judicial principles. Punishment must be measure for measure: “then shall ye do unto him, as he had purposed to do unto his brother.” Judges sitting in judgment represent the LORD: “before the LORD, before the priests and the judges.” They hear accuser and accused, investigate, and freely reach conclusions through their judgment: “And the judges shall inquire diligently; and, behold, if the witness be a false witness, and hath testified falsely against his brother.” In principle they need neither two witnesses to initiate trial nor two to convict.
The law also demonstrates the danger that one witness may bring an innocent person’s conviction. The Torah therefore innovates that, although judges may decide through investigation and judgment without depending on two witnesses, a legal proceeding may not begin on one accusing witness alone.
It achieves this by retaining the original law and prefacing “One witness shall not rise up against a man…” “Shall not rise up” means not that the verdict cannot stand on one witness, but that the trial shall not arise: it shall not begin from one witness’s accusation. “Rise up” has the same meaning as “If an unrighteous witness rise up against any man,” describing the proceeding’s beginning rather than its end.
The Torah thus maintains measure-for-measure punishment and judges’ freedom to decide according to understanding while preventing conviction on a single witness by blocking proceedings at the outset when there is only one accuser.
