If, Heaven forbid, a person is in mourning on Pesah – meaning, he is within twelve months of a parent’s passing, or within thirty days of the death of another family member – is he required or even allowed to perform Haseba (leaning) at the Seder? The purpose of leaning at the Seder is to express freedom and royalty, which may not be appropriate when a person is mourning the loss of a loved one, and thus the question arises as to whether the Haseba requirement applies during Abelut (mourning).
Indeed, the Bah (Rabbi Yoel Sirkis, Poland, 1561-1640), in Siman 472, rules that a mourner should not perform Haseba at the Seder. He notes that in any event there are those who maintain that the requirement to lean does not apply nowadays, and thus a mourner should refrain from leaning at the Seder. This view, however, does not represent the consensus among the Halachic authorities. Several authorities, including the Hikekeh Leb and Zera Emet, maintain that a mourner does lean at the Seder. This is also the view of the Kaf Ha’haim (Rav Yaakov Haim Sofer, Baghdad-Israel, 1870-1939), who writes (Orah Haim 472:29) that a mourner should perform Haseba at the Seder, but if possible, he should preferably do so "Be’derech Shinui" – meaning, in an unusual manner. One way of doing this would be to lean on the person sitting next to him, rather than leaning back on his chair. This is the ruling accepted by Rav Shemuel Pinhasi (contemporary), in his work Haim Va’hesed (p. 311; listen to audio recording for precise citation).
Summary: A mourner, Heaven forbid, is required to perform Haseba (leaning) at the Seder, though if possible, he should do so in an unusual manner, such as by leaning on the person sitting next to him.
