Right or Left-Handed Tefillin

Question: Our son is turning bar-mitzva in a few months. While he is generally right-handed, and writes English with his right hand, he writes Hebrew with his left hand. Which arm should he wear his tefillin on?

Answer: The Gemara (Menachos 36b) teaches that one who is right-handed wears the tefillin shel yad on his left arm while one who is left-handed wears it on his right arm.

The Shulchan Aruch (OC 27:6) cites a machlokes regarding one who writes with one hand, but performs most other activities with the other hand. The Rema notes that the accepted practice is to determine this by which hand is used for writing.

The Magen Avraham (27:10) cites the Bach (OC 27:2), who argues writing is not the overriding factor when it conflicts with majority of actions or natural hand usage. Nonetheless, the Magen Avraham dismisses this, stressing that we follow the hand used for writing.

R’ Ovadia Yosef (Yabia Omer OC 6:2:4) clarifies that there is no distinction between Hebrew and other languages for this purpose. Therefore, where a person writes different languages with different hands, and there is no clear dominant writing hand, writing is no longer decisive, and one instead follows the hand used for most of his daily activities.

Similarly, R’ Shmuel Wosner (Shevet Halevi 5:5) writes that one who writes two languages with different hands, so that there is no consistent writing hand, is not defined by writing alone. In such a case, since the writing factor is unclear, he rules that the person should follow his general use of the hands, and therefore wear tefillin on the left arm like most people (see Mishne Halachos 6:9).

In conclusion, one who uses two hands for writing but is otherwise right-handed, is considered to be right-handed and should wear his tefillin on his left arm.