Should a lefty try to train himself to become a righty in order so he can wear the Tefillin on his left hand?[1]

Some Poskim[2] encourage one to do so. Other Poskim[3], however, discourage one from doing so. Practically, one is not to do so without first discussing the matter with his rabbi and doctor.[4]

[1] See Piskeiy Teshuvos 27:15

[2] Halef Lecha Shlomo 11; Shoel Umeishiv Tinayan 2:58; Avnei Tzedek 3; Maharsham 3:299; Maharash Engel 3:13; Divrei Yoel 1:3; Divrei Yatziv 1:9

[3] Shevet Halevi 9:6; Teshuras Shaiy 2:85; See Piskeiy Teshuvos 27:15 footnotes 119-120

[4] Rav Nasan Gurray of Buffalo relates that the Rebbe told his father that it is not medically wise to try to change one’s handedness from a lefty to righty. [See Hiskashrus 574; Dinei Iter 5:14]