Talmud for Sotah 1:1
משנה המקנא לאשתו רבי אליעזר אומר מקנא על פי שנים ומשקה על פי עד אחד או על פי עצמו רבי יהושע אומר מקנא על פי שנים ומשקה על פי שנים:
From when may one recite Shema in the evening? From the time the Kohanim go in to eat their Terumah (produce consecrated for priestly consumption). Until the end of the first watch, says Rabbi Eliezer. And the Sages say: Until [astronomical] midnight. Rabban Gamliel says: Until the break of dawn. It once happened that his [Rabban Gamliel’s] sons came from a house of feasting. They said to him: We have not recited Shema. He to them: If dawn has not broken, you are obligated to recite it. And it is not only in this case that they said it! Rather, in all cases where the Sages said "only until midnight," the obligation remains until the break of dawn. [e.g.] Burning the fats and limbs [of the sacrifices, on the Temple altar] — the obligation is until the break of dawn. [e.g.:] All [sacrifices] which may be eaten for one day — the obligation is until the break of dawn. If that is so, why did the Sages say, "until midnight?" To distance a person from transgression.
Jerusalem Talmud Sanhedrin
In civil suits, one who argued for credit may argue for debit and one who argued for debit may argue for credit; but in criminal suits one who argued for conviction may argue for acquittal but one who argued for acquittal is barred from arguing for conviction.