Responsa for Yevamot 211:14
דתניא (ויקרא כב, יח) יקריב אותו מלמד שכופין אותו יכול בעל כרחו ת"ל לרצונו הא כיצד כופין אותו עד שיאמר רוצה אני וכן אתה מוצא בגיטי נשים כופין אותו עד שיאמר רוצה אני
How then [are the two texts to be reconciled]? He is subjected to pressure until he says, 'I am willing'. And so you find in the case of letters of divorce for women: The man<span class="x" onmousemove="('comment',' Who refuses to give a divorce. ');"><sup>34</sup></span> is subjected to pressure until he says, 'I am willing'.<span class="x" onmousemove="('comment',' Cf. Kid. 50a, B.B. 48a, Ar. 21a. ');"><sup>35</sup></span> Raba reported in the name of R. Sehora in the name of R. Huna: <i>Halizah</i> may be arranged even though [the parties]<span class="x" onmousemove="('comment',' The levir and his sister-in-law who apply for a halizah to be arranged for them. ');"><sup>36</sup></span>
Teshuvot Maharam
A. Bediabad, in this case, means after the rite was performed. Nevertheless, the aforementioned performance of the rite is invalid, for a different reason: the shoe used was sewed with flaxen thread and, therefore, was never fit for this purpose. Since, however, the levir performed an invalid rite of halitzah, neither he nor his brothers are now permitted to marry the widow. Halitzah by the same levir being the only manner of releasing her, he may be forced, by persuasion or by flagellation, to repeat the rite with the proper shoe. For now the Mitzvah revolved on him alone, and we are permitted to scourge a Jew until he perform the required Mitzvot.
This Responsum is addressed to Rabbi Menahem of Würzburg.
SOURCES: Am I, 93, 94.