Rav Schachter has previously indicated that the use of force to encourage the husband to give a get is permitted - even without a ruling of beis din. His recording where he mentioned the appropriateness of the use of violence have been removed from the YU website. See his letter at the end of this post.
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From the end of the following post
The violent attack against Aharon Friedman was at least partially the result of the incitement to violence against Aharon by various rabbis and organizations. In this letter (see link below) that was publicized by ORA, Rabbi Hershel Schachter calls for Aharon to be physically beaten. It is not yet known whether Rabbi Schachter was involved in hiring the thugs that attacked and attempted to kidnap Aharon on Tisha B'av.
One of the sources Rabbi Schachter cites in the letter against Aharon (Rabbi Akiva Eiger) is referenced in an audio lecture by Rabbi Schachter that is on Yeshiva University’s website: http://www.yutorah.org/lectures/lecture.cfm/739308/Rabbi_Hershel_Schachter/Options_for_Helping_Agunot# as grounds for beating someone over a get. (It is ironic that Rabbi Eiger writes about a husband who is leaving the city of the marital residence and that immediate action was necessary, whereas in this matter it was Epstein who left the city of marital residence with the child and abused the beis din process so that her abduction of the child would be treated as a fait accompli in court.)
In the letter, Rabbi Schachter says that Aharon's situation is the same as "a slave whose master provides for him a Canaanite maidservant, that until now it is has been permissible, and now it is forbidden." In the audio, he explains that in such a situation the slave, or, as he writes in the letter, Aharon, should be beaten. Furthermore, Rabbi Schachter specifically writes in the letter that any person can take the law into his own hands [to beat Aharon].
See in particular:
4:00 - beat someone over a get (citing Rabbi Akiva Eiger)
4:30 - beat a slave for wrongfully remaining married to maidservant, analogizing this case to the get case, and that anyone can take upon himself to take the law into their own hands to beat the person
9:10 - beat someone up over a get
10:20 - bludgeon someone to death over a get
13:33 - have right to beat someone over a get (citing Rabbi Akiva Eiger)
26:50 - beating for a get with a baseball bat
Rabbi Schachter’s letter can be found at Daas Torah here: http://daattorah.blogspot.com/2012/04/rav-schachter-i-relied-on-rav.html
The reference to Bava Kama 28a in the letter is referring to beating a former slave to prevent him from sinning. It is permitted to beat him - even without the authorization of a beis din
Come and hear: Whence is derived the ruling that in the case of a [Hebrew] bondman whose term of service, that had been extended by the boring of his ear,9 has been terminated by the arrival of the Jubilee year10 if it so happened that his master, while insisting upon him to leave, injured him by inflicting a wound upon him, there is yet exemption? We learn it from the words, And ye shall take no satisfaction for him that is . . . come again . . .11 implying that we should not adjudicate compensation for him that is determined to come again [as a servant].12 [Does not this prove that a man may take the law into his own hands for the protection of his interests?]7 We are dealing here with a case where the servant became suspected of intending to commit theft.13 But how is it that up to that time he did not commit any theft and just at that time14 he became suspected of intending to commit theft? Up to that time he had the fear of his master upon him, whereas from that time14 he is no more subject to his master's control.10 R. Nahman b. Isaac said: We are dealing with a bondman to whom his master assigned a Canaanite maidservant as wife:15 up to the expiration of the term this arrangement was lawful15 whereas from that time this becomes unlawful.16