ותניא היה ר"ט אומר כל מקום שאתה מוצא אגוריאות של עובדי כוכבים אע"פ שדיניהם כדיני ישראל אי אתה רשאי להיזקק להם שנאמר (שמות כא, א) ואלה המשפטים אשר תשים לפניהם לפניהם ולא לפני עובדי כוכבים דבר אחר לפניהם ולא לפני הדיוטות
And it is taught in a baraita that Rabbi Tarfon would say: With regard to any place where you find gentile courts [agoriot], even if their laws are like Jewish laws, you may not attend them, as it is stated: “Now these are the ordinances which you shall set before them” (Exodus 21:1). It is derived from here that one may go to court only before them, i.e., Jewish judges, and not before gentiles. Alternatively, it is derived that one may go to court before them, i.e., ordained judges, and not before ordinary people.
לפניהם BEFORE THEM — but not before the heathens. Even if you know that in the case of a particular matter of law they will decide it in the same way as Jewish law would, do not bring it before their courts; for he who brings Israel’s law-cases before the heathens defames the Name of the Lord and pays honour to the name of the idol (in the name of which the heathen court administers justice), thereby giving it undue importance, as it is said, (Deuteronomy 32:31) “For their rock is not as our Rock that our enemies should be judges over us”, which implies: when our enemies are judges over us (i. e. if we make them judges over us) it is a testimony to the superiority of that which they reverence (their idol) (Midrash Tanchuma, Mishpatim 3).
כָּל הַדָּן בְּדַיָּנֵי עַכּוּ''ם וּבְעַרְכָּאוֹת שֶׁלָּהֶן אַף עַל פִּי שֶׁהָיוּ דִּינֵיהֶם כְּדִינֵי יִשְׂרָאֵל הֲרֵי זֶה רָשָׁע וּכְאִלּוּ חֵרֵף וְגִדֵּף וְהֵרִים יָד בְּתוֹרַת משֶׁה רַבֵּנוּ שֶׁנֶּאֱמַר (שמות כא א) "וְאֵלֶּה הַמִּשְׁפָּטִים אֲשֶׁר תָּשִׂים לִפְנֵיהֶם" לִפְנֵיהֶם וְלֹא לִפְנֵי עַכּוּ''ם לִפְנֵיהֶם וְלֹא לִפְנֵי הֶדְיוֹטוֹת...
All who seek justice in idolatrous judges and in their courts, even when their laws are similar to the laws of Israel, this person is evil. It is as if they spite, curse, and raise a hand against the Torah of Moshe. As it says, "These are the rules that you shall set before them" - before them and not before idolaters, before them and not before ordinary people...
שלא לדון בדיני עכו"ם ובו ד סעיפים:
אסור לדון בפני דייני עכו"ם ובערכאות שלהם (פי' מושב קבוע לשרים לדון בו) אפי' בדין שדנים בדיני ישראל ואפי' נתרצו ב' בעלי דינים לדון בפניהם אסור וכל הבא לידון בפניהם הרי זה רשע וכאלו חירף וגידף והרים יד בתורת מרע"ה:
It is forbidden to appear for trial before heathen Judges and in their Courts of Law, [the locality wherein] permanent judicial sessions are held by the [civil] magistrates, even regarding a lawsuit that they [the heathen Judges] adjudicate like the Israelite Law. Even if the two litigants agreed to be tried before them, it is forbidden. And whosoever appears for trial before them is considered a wicked person and is as though he blashphemed, reproached and rebelled against the Torah of Moses, may he rest in peace.
Whence do we know that litigants in Israel who are involved in litigation against each other must not turn to an idolatrous judge for a decision in their suit, even though they know that he will judge them according to Israel’s laws? Because it is forbidden (for Jews) to argue before them? Scripture states: Which thou shalt set before them. That is, before the children of Israel and not before the other nations of the world. For anyone who shuns Israel’s judges and testifies before an idolatrous judge renounces the Holy One, blessed be He, first, and later renounces Israel’s law, as it is said: For their rock is not our Rock, and our enemies’ judge (Deut. 32:31). To what may this be compared? To a patient examined by a doctor. He tells the members of (the patient’s) household: “Give him whatever food he desires, withhold nothing from him.” (Later) he visits another patient and advises his household: “Be careful that he does not eat or drink certain things.” They remonstrate with him, saying, “One patient you permit to eat whatever he wishes, while the other you advise not to eat certain things.” Thereupon he replied: “The first patient will not survive, and that is why I told them not to deny him anything, for whether he eats or not, he will die. However, the other patient will live, and so I advised him to eat only certain things lest his illness be aggravated.” So, too, are the ordinances of the idolaters, as is said: For the statutes of the people were vanity (Jer. 10:3), and it is written elsewhere: Wherefore I gave them also statutes that were not good, and ordinances whereby they should not live (Ezek. 20:25). However, to Israel I gave commandments and desirable statutes, as it is said: Ye shall therefore keep My statutes, and My ordinances, which if a man do, he shall live by them (Lev. 18:5).