Is it permitted for one who has a monetary claim to threaten another Jew with legal action in a secular court if he does not intend to truly do so and will in the end go to a Beis Din?
* Important note: The below discussion only refers to a case that the individual has not received permission from the Beis Din to go to a secular court or to be allowed to threaten to do so. However, if he has received permission from the Beis Din to go to a secular court, or if according to Torah law it is permitted for him to do so even without receiving permission from the Beis Din [such as if the defendant is not religious or is a Gentile and one knows for certain that he will not agree to show up to the Beis Din], then obviously one may threaten and even go to a secular court, and the below discussion is irrelevant.
A. Background of the general prohibition of going to a secular court:
It is forbidden to make judicial claims in the presence of gentile judges and in their courts. This applies even if their legislation concords with Torah law, and would give the same verdict as a Jewish court. This applies even if both parties [plaintiff and defendant] agree to be judged in the gentile court system. Anyone who makes a judicial claim in a gentile court house is a Rasha, and is considered to have humiliated and blasphemed and raised his hand against the Torah of Moshe Rabbeinu. Now, we will address the question regarding whether it is forbidden to even threaten to do so, or if making a mere threat is permitted.
B. The law regarding making a threat:
From some Poskim it is implied that it is forbidden to even threaten to take a Jew to a secular court, and that this applies even if he is using this threat as a means to pressure him to go to a Beis Din. However, others dismiss these implications as baseless. Practically, many Rabbanim rule that it is forbidden for a Jew to even threaten another Jew that he will take him to secular court, even if he does not plan on doing so due to the prohibition, and rather he must tell him that he will take him to a Beis Din. [It is however permitted to tell him that if he refuses to listen to the ruling of the Beis Din, or if he refuses to go to a Beis Din at all, then he will receive their permission to take him to a secular court.] Likewise, it is permitted for him to write him a letter saying that he reserves all his rights and powers that are available to him to fight his case, and he may even mention the word court, without explicitly mentioning the secular court. However, other Rabbanim rule that it is permitted to threaten another Jew to take him to secular court if indeed one does not plan on doing so, and the individual that he is threatening truthfully owes him money according to Torah law. Practically, one is to avoid making even empty threats to take another Jew to a secular court unless all other options have been exhausted and he speaks to a Rav for guidance prior to doing so.
Having a lawyer send the person a threat of a lawsuit: According to the stringent opinion above, it is certainly forbidden to have a lawyer send an individual a threat of a lawsuit in the secular courts. However, it is permitted for him to have a lawyer write a letter to the individual saying that his client reserves all his rights and powers that are available to him to fight his case, without explicitly mentioning taking him to secular court. However, according to the lenient opinion above, is permitted for him to do so even if he explicitly mentions taking him to a secular court.
Filing a case in the courts and having a court appearance date sent to the person: Even amongst the lenient opinions brought above, many of them rule that it is nevertheless forbidden to file a lawsuit in a secular court [without receiving prior permission from a Beis Din] even if one’s intent is not to go through with it and simply to threaten the individual and pressure him to pay his dues. It is even forbidden to use this filing of a lawsuit as a tactic to force him to go to Beis Din unless one has already tried to take him to Beis Din, and he refuses to comply, in which case the Beis Din can give him permission to go to a secular court.
The law if the individual who was threatened paid money as a result: If as a result of the threat to take him to a secular court the two parties came to a compromise regarding the compensation claims, then the compromise is valid even if the threat was illegal. Nonetheless, in certain cases, a threat of legal action in a secular court can be used to invalidate an agreed upon compromise, and thus in all cases of doubt the matter is to be brought before a Beis Din.
Although the matter of whether one may threaten secular court action against another Jew without permission from a Beis Din, but without intent to actually carry out, is debated amongst the Poskim of today, practically it is not to be done unless all other options have been exhausted and one has discuss this matter with a Rav.
 See Rama C.M. 26:2; Rav Silman in Hayashar Vehatov Koveitz 4:65; Beshivilei Haparsha p. 229; Kuntrus Betzedek Tishpot p. 17 and 30; Shaareiy Shlomo 4; Erkaos Behalacha p. 38; Mayan Omer 10:23
 Daas Kedoshim 26:2
 Michaber C.M. 26:1; Braisa Gittin 88b
 Michaber ibid; Ramban on Mishpatim ibid
 Michaber ibid; Tur 26; Rambam Sanhedrin 5; Rashi Mishpatim
 Implication of Michaber C.M. 34:20 “One who hates his friend and says to him in front of others that he will inform on him to Gentiles and cause his money to be confiscated then he is invalid for testimony” and Michaber C.M. 388:8 in name of Mordechai“A Mosser is invalid for testimony from the moment that he publicly says that he will go and inform on someone to the Gentiles even if he has yet to do so”; See also Shut HaRosh 17:4, Teshuvos Hageonim in Shaareiy Tzedek 4:1-1/9 from which it is implied that threatening to go to secular court gives a person the status of a Mosser. [However, one can argue that this only applies if he publicly makes this statement in public and not when sending a personal private message to the defendant. See Shacha 388:54; Radbaz 1:348; Kuntrus Betzedek Tishpot p. 17 and 30. Likewise, one can argue that it only applies when making the threat to Gentiles who may kill the person, and not regarding simply a secular court. See Beis Yitzchak Y.D. 2:49-12; Kuntrus Betzedek Tishpot p. 17]; Possible implication of Rama C.M. 26:1 who rules “even if he does not bring the case to a Gentile court but simply uses Gentiles to force the defendant to appear before a Beis Din, then he is fit to be hung on the pillar” that perhaps the prohibition of using Gentiles to force an individual to go to Beis Din includes even if one simply threatens him [However, the counterargument to this is that the Rama using Gentiles to physically force him to go however to threaten him to use Gentiles to force him to go t and perhaps remains permitted he Rama never discussed and perhaps remains permitted]; Implication of Shut Tashbeitz 4 Tur 3:3 “One does not have to wait until he actually goes to the secular court to excommunicate him, but rather as soon as he threatens and says that he will do so he is to be protested and if he does so he is to be told that if he goes he will be excommunicated.” [While this statement does imply that even threatening is forbidden, one can argue that he refers to a case that the person truly is planning to go through with his threats, or at least he does not tell the Beis Din otherwise. However, if he plans to threaten the individual alone and upon being confronted by the rabbis he plans to tell them the truth that it was just a threat and he does not plan to do so, then perhaps this would be permitted. Se Mayan Omer 10:23] Implication of Midrash Tanchuma Parshas Mishpatim, brought in Shaareiy Shlomo 4
 See our counterarguments in the brackets within the previous footnote, and the Sefarim cited there
 Conclusion of Shaareiy Shlomo 4 based on Midrash Tanchuma ibid and possibly also Rosh ibid; My Teacher Harav Yaakov Yosef z”l; Rav Silman ibid based on the implications from Michaber C.M. 34:20 and 388:8; Rav Mordechai Gross in Tel Talpiyos on Rama C.M. 26:1
 Rav Silman ibid; Shaareiy Shlomo 4; As not only does this text not threaten the person to take him to secular court but furthermore in truth explicitly exclude it, as he is writing that he will only use those methods that are available to him which should be interpreted to include taking him to a Beis Din, and if necessary as decided by the Beis Din, then to take him to secular court. [Rav Silman ibid]
 Shut Maharil Diskin Kuntrus Reshimos 20; Rav Ovadia Yosef in Mayan Omer 10:23; Rav Asher Weiss, in Kuntrus Betzedek Tishpot p. 17, and so rules Rav Katzenelonbogan in Kuntrus Betzedek Tishpot p. 30
 The reason: As the prohibition of going to a secular court is specifically in going there and not in simply threatening to go there.
 In general, just as it is forbidden to think of performing a transgression so too it should be forbidden to speak about performing a transgression, and hence regardless of the Mosser and Erkaos discussion brought by all the above Sefarim, it should be forbidden due to this alone, as how can it be permitted for one to say that he will do a sin, and as is known that thoughts brings to speech and speech brings to action, and hence speaking of doing the sin is opening the gateway to its actual transgression. Thus, clearly, one should not threaten another Jew to take him to secular court simply out of anger, and is rather to use all of the permitted methods he has available through the Beis Din. If, however, one has exhausted all other efforts, then seemingly one may be lenient to threaten to take him to a secular court, as this is no different than the allowance for one “to take judgment into his own hands” when he has a secure claim. Practically, however, if it has come to this point that he cannot resolve the matter in a Beis Din, then he should simply ask them for permission to take him to a secular court and not resort to empty threats.
 Rav Silman ibid; As not only does this text not threaten the person to take him to secular court but furthermore in truth explicitly exclude it, as he is writing that he will only use those methods that are available to him which should be interpreted to include taking him to a Beis Din, and if necessary as decided by the Beis Din, then to take him to secular court. [Rav Silman ibid]
 See Shut Maharil Diskin Kuntrus Reshimos 20; Shut Yeishiv Moshe C.M. p. 222 that Harav Elyashiv did not answer him a definitive answer to the negative or affirmative regarding this question
 Rav Asher Weiss in Kuntrus Betzedek Tishpot p. 17; Rav Bentzion Wozner in Koveits Divrei Mishpat; Erkaos Behalacha p. 38; See Tashbeitz 2:290
Other opinions: Some Poskim rule that even filing a lawsuit in secular courts is permitted so long as he does not plan to go through with it. [Shut Maharil Diskin Kuntrus Reshimos 20; See Shaareiy Shlomo 4]
 Possible understanding of Rama ibid that perhaps the prohibition of using Gentiles to force an individual to go to Beis Din begins even if one simply threatens him; Rav Bentzion Wozner in Koveits Divrei Mishpat as the mere fact that one evens files a case in the secular court already shows that he honors them and blasphemes our Torah
 Maharashdam C.M. 13 in name of Maharik 185; Mahariy Ben Leiv 1:98; Seder Hadin 4:90
The reason: As it is common for people to make threats that they do not plan on following through with [i.e. Gazim Velo Avid], as well as that threatening to take him to secular court is not a real threat as perhaps he will lose the case as happens many times. [Maharik ibid]
 See Shut Rama 22; Maharit 2:4; Divrei Chaim 2:3; Rav Poalim 2:15; Mahariy Ben Leiv 1:98