The Rosh (7:20) comments that the minyan that R. Eliezer was trying to form was for the purpose of a biblical mitzvah, such as reading Parshat Zakhor. Thus, the Rosh is understood to maintain that the biblical obligation of remembering the attack of Amalek requires a minyan and a sefer Torah (Some challenge this reading of the Rosh, though; note Resp. Binyan Shelomo, I, 7 as well as the comments of R. David Metzger in the journal Orayta, XVII, p. 339). This is also understood to be the view of Tosafot (Berakhot 13a, s.v. b’lashon, and Megilah 17b, s.v. kol). By contrast, the Sdei Chemed (Ma’arekhet ha-ayin, X) cites Rambam and Ramban as disagreeing. R. Yitzchak Ze’ev Soloveitchik (quoted in R. Moshe Sternbuch’s Resp. Teshuvot V’Hanagot, II, 353) understands Rambam’s position to be that the public reading of Parashat Zakhor is an obligation no stronger than that of the rest of the “four Parshiyot” read on special shabatot at that time of the year. Similarly, the Mishnah Berurah cites the Terumat haDeshen (#108) as assuming a biblical obligation of minyan, but he himself finds this notion to be without source, and finds a rabbinical obligation of minyan to be equally if not more likely. (See also Ginzei Chaim, Orakh Chaim 685 (7):2; Resp. Tehilot David (I, 144); Resp. Shema Yisrael (94); R. Meir Rosenberg, in the journal HaPardes (IV, 11:91); and Nachalat Shimon (Melakhim I, Vol. II, 55:6).

Within those who felt the obligation inherently requires a sefer Torah, a minority opinion would allow even a disqualified sefer (See Resp. Maharshag II, 141), while most authorities assume that the sefer must be valid (See Resp. Maharam Shick, Orach Chaim 336, and Sefer haMitzvot 605; Resp. Minchat Elazar, II, 1; and Mo’adim U’Zemanim, II, 166), and some require an especially flawless sefer (mehudar) (see Resp. Teshuvot V’Hanagot (II, 353). The Resp. Amudei Ohr (124) suggests that a source for an obligation of sefer Torah can be found in the verse (Shemot 17:14) “Write this as a rememberance in the Book”. Similarly, the Maharam Shick (Sefer haMitzvot 604) offers a rationale for minyan: the obligation to remember Amalek is intertwined with the commandment to do war with Amalek, a concept which is incumbent upon the community as a whole. Thus, it follows that the formal remembrance of Amalek would require the official sampling of the community at large embodied in a minyan. (See also Keren Orah, Berakhot 5a, and note related discussions on the parameters of the communal reading in the journal Zekhor L’Avraham [5752, pp. 352-359, R. Chaim David Halevi, and 5750, pp. 163-164, R. Ya’akov Edelstein] and in Resp. Tehilot David I, 82).

The notion that remembering Amalek, in whatever fashion, must be done once a year merits special discussion as well. As the Torah specifies no time frame, one might equally surmise a daily obligation on one extreme and a once-in-a-lifetime obligation on the other. The Chatam Sofer is cited by one of his most prominent students, R. Moshe (Maharam) Shick (Resp., 605), as explaining this idea based on a shiur shikchah, or timeframe that leads into forgetting, of twelve months. Such a time period is alluded to in two Talmudic texts. In one (Berakhot 58b) we are told that the deceased are “forgotten from the heart” after twelve months ; in another, we learn that one who has lost property is presumed to have despaired of finding it (ye’ush) after twelve months (Bava Metzia 28a).

Building on this foundation, the Maharam Shick emerges with a significant stringency. In the event of a leap year, thirteen months pass between one Shabbat Zakhor and another; thus, a “shiur shikchah” would elapse without the memory being refreshed. Consequently, in those years, an obligation exists on the individual to be particularly attentive during the regular reading of Parashat Ki Tetze, to fulfill this obligation before such a scenario ensues. [As to what obligations of intent would fall upon the reader and the listener, see R. Tzvi Pesach Frank’s comments in both Mikra’ei Kodesh (Arba Parshiyot, 6) and Resp. Har Tzvi (Orach Chaim 58) as well as Resp. Chatam Sofer (Orach Chaim 15{1]), and the journal Mesorah (Vol. X, p. 52).] However, it is questionable whether even Chatam Sofer himself accepted this conclusion [See Resp. Chatam Sofer(Even haEzer I, 119), as well as Resp. Shevet haLevi (I, Yoreh Deah 132:4); Resp. Divrei Yisrael (II, Likutei Torah, 79); Sefer Ohel Yehoshua/Maset haMelekh al haTorah (Purim, 1), and the journal Beit Aharon V’Yisrael (IV:4, p, 541).].

On a more fundamental level, the Satmar Rebbe, R. Joel Teitlbaum (Resp. Divrei Yoel, 33), questioned the actual Talmudic support for a “shiur shikchah”. Yes, the departed begin to be forgotten after a year; however, that is after a year of greiving and conciously attempting to move forward, a situation markedly different from that involving an active obligation to remember Amalek. Yes, the owner of lost property despairs after twelve months, but that is different than forgetting. Rather, submits R. Teitlbaum, the yearly observance is a result of the desire of the Rabbis to affix the remembrance to the closely linked occasion of Purim the following week. [See also S'dei Chemed, ma'arekhet ha-zayin, 13; Resp. Arugat haBosem, O.C. 205; Resp. Divrei Yisrael, (I, 213); Resp. Minchat Elazar (II, 1:5); and Resp. Shraga haMeir (VI, 100:1 and 116).]

The inclusion of women in the obligation of remembering Amalek is the subject of much controversy. This issue flows directly from the previous one: Magen Avraham (O.C. 685) notes that since in theory the obligation can be fulfilled at any time, it does not enter the category of "time-bound" (mitzvat aseh she-ha-zeman grama) that would exempt women. Likewise, Resp. Binyan Tziyon (Chadashot, 8) obligated women to attend the yearly reading, citing R. Nathan Adler, revered mentor of Chatam Sofer. The Sefer haChinukh (603), however, did exempt women, considering the obligation to be inextricably connected to warfare and thus exclusive of women. [Note Marcheshet,(I, 22) and Resp. Avnei Nezer (O.C. 509) who, from different approaches, identify zeman grama as the issue with warfare. Note as well the very different approach attributed to R. Yosef Dov Soloveitchik in the journal Mesorah (X, p. 52). See Resp. Binyan Shlomo (7); Mikraei Kodesh (arba parshiyot, 5); Resp. Rabaz (III,73)Resp. She'alat Shaul (92); Divrei Shlomo {Schneider} (I, 37); the journal HaPardes (XL, 6:48; LVI, 5:29; LXII, 6:30; and LXIV, 6:33)] . Resp. Toras Chesed (O.C. 37) countered this point by observing that obligatory warfare, milchemet mitzvah, does incorporate women. [See also Resp. Minchat Elazar (II, 1:5). Consequently, Torat Chesed does obligate women, but not necessarily with a valid sefer. See also Resp. Shraga haMeir (VI,116).] This point is responded to by Resp. Zekher Simchah (73) who explains that inclusion to be limited to warfare serving the purpose of settling the land of Israel. On a more basic level, Minchat Chinuch questioned the authority of the Sefer haChinuch to exempt women from a biblical commandment, especially without an explicit source. [See also Resp. Hitor'rut Teshuvah (5); Resp. Arugat haBosem (I, 205-207); Resp. Maharil Diskin (Kuntres Acharon, 101-102); Resp. Minchat Yitzchak (IX, 68); Resp. Minchat Aharon (I,431 and II, 137); Resp. Divrei Yisrael (I, 214, and II, glosses to O.C. 685); Resp. Kinyan Torah baHalakah (VII,53); Resp. Divrei Yatziv (O.C. 288, 289).]