Hello Rabbi, I hope all is well. I had a quick question which I hope you can answer: is it permissible to learn הלכות אבילות (Laws of Mourning) on shabbat (i.e. those laws discussed in the sugyot in Mo’ed Katan and Tur/Shulchan Aruch)? I am aware that one is not supposed to learn sad or morbid topics on Shabbat. If you could let me know, I would greatly appreciate it. Thank you!

ב"ה Shalom, There are restrictions for learning Torah on Tishav B'av when we are in national mourning and for a person during Shivah. (see Shulchan Aruch Orach Chaim 554:1 and Yoreh De'ah 384:4) There are no restrictions as to what Torah to learn on Shabbat. Don't forget we publicly read Parshat Bechokotai and Ki Tavo on shabbat, where there is plenty of sad material. I saw in the name of Rav Meir Mazuz שליט"א,, that one may read ספר איוב (the book of Job) on Shabbat just as it was read to the Kohen Gadol on Yom Kippur as it says in the Mishna Yoma 1:6). On the other hand, there are those who have reservations about learning Hilchot Avelut unless one is in mourning according to the Chatam Sofer ( שו"ת חת"ם סופר יור"ד סי' שמ"ו) However, Rav Shlomo Zalman Oirbach zt"l said that there is no reason to refrain from such learning, and he who fulfills a mitzva shall not no evil. הליכות שלמה מועדים עמ' תל"ט note 35. (See also ספר חסידים סימן קה, רסא ) All the best