Translation:Shulchan Aruch/Orach Chaim/38
38: Who is Required to Put on Tefillin and Who is Exempt.
1 One who has an intestinal sickness is exempt from tefillin. Gloss: Even if he is not in discomfort. But for other ill people, if one is in discomfort from the illness and is not level-headed/aware, then he is exempt. And otherwise, he is required. [Mordechai and Orchot Chayim and Maimuni Chapter 4].
2 For one to whom it is clear that he cannot pray without being flatulent, it is better to miss praying than to pray with a dirty body [and see below, Chapter 80]. And if it seems to him that he can manage to keep a clean body in the time of reading the Shema, he should put on tefillin between Ahava and reading the Shema and say the blessing.
3 Women and slaves are exempt from tefillin because it is a time-dependent positive mitzvah. Gloss: And if the women want to be strict upon themselves, we object [Kol Bo].
4 One who puts on tefillin must be careful to avoid idly lusting after women in his thoughts.
Gloss: And if he can't avoid such passing thoughts, it is better that he not put them on. [Kol Bo and Orchot Chaim].
5 A mourner on the first day is prohibited from putting on tefillin. From then on, he is required, even if new people came to console.
6 And on Tisha Ba'av, one must put on tefillin (and see below Chapter 555).
7 A groom and his shoshvinim (meaning his friends who are celebrating with him) and all people of the chuppah are exempt because drunkenness and lightheadedness are frequent.
8
Those who write tefillin and mezuzahs, they and their traders, and the traders of their traders, and everyone whose business is work on behalf of Heaven, are exempt from putting on tefillin all day except during reading the Shema and prayer.
Gloss: And if they needed to do their work during the reading of the Shema and prayer, then they are exempt from reading the Shema and from prayer and from tefillin, as everyone who is busy performing a mitzvah is exempt from another mitzvah if it will trouble him to do the other one. But if one can do both at the same time without troubling oneself, one should do both (Notes of Ashiri in the name of Or Zarua and the Ran, Chapter "One Who Sleeps").
9 One who is troubled or one who does not have his wits about him is exempt because it is prohibited to have one's thoughts stray from them.
10 A Torah reader is exempt from putting on tefillin for the entire day except for the time of reading the Shema and prayer.
11 One should not remove tefillin while facing one's teacher, instead one should face to another side because of his awe and remove so it is not in his face.
12 One who needs tefillin and a mezuzah and he cannot afford to buy both of them should buy tefillin first.
13 Those who have been excommunicated and those with leprosy are prohibited from putting on tefillin.