The Shulhan Aruch discussed the Mukse status of Tefilin on Shabbat. Tefilin are not worn on Shabbat, and thus the question is whether they may be moved on Shabbat. The Zohar HaKadosh (Midrash Ne’elam) teaches that not only is there no Misva to wear Tefilin on Shabbat, but it is prohibited to do so. That is also the implication of Maran in the Bet Yosef, Siman 31. Therefore, Hacham Ovadia, Rav Moshe Halevy and the Ben Ish Hai all rule that Tefilin have the status of "Kli She’melachto L’isur"-a utensil whose primary function is prohibited. Accordingly, the Tefilin may only be moved for two purposes.
1. "L’sorech Gufo"-their innate function. For example, a teacher may handle the Tefilin to show them to students as a demonstration.
2. "L’Sorech M’komo"-for its place. If the Tefilin were in the way, they may be moved to make room for something else.
The question is whether one may carry his Kuracha, containing both his Tallit and Tefilin, on Shabbat. The Kuracha is designated a "Basis"-base for both forbidden items (the Tefilin) and permitted items (the Tallit and Siddur), and therefore may be moved. If the Tallit can be removed without moving the Tefilin, that is best. However, if the Tefilin are in the way and prevent him from accessing his Tallit, he may move the Tefilin, since this is considered "L’Sorech M’komo"-for its place.
Hacham Ovadia (Halihot Olam) poses a very strong question. Why is it permitted to remove the Tallit from the Kuracha? Once the Tallit is removed, it is no longer a Basis for permitted and forbidden items. It remains a "Basis L’davar Ha’asur," and becomes Mukse and may not be moved. This would be an apparent violation of "Bitul Keli MeHechano" suspending a utensil from function. Before the Tallit was removed, it was permitted to move the Kuracha, and afterwards it is prohibited.
Hacham Ovadia suggests that the Halacha relies on the minority opinion that "Kli She’melachto L’isur" does not create a Basis, and therefore the Tefilin do not render the Kuracha Mukse, and there is no issue of "Bitul Kli MeHechano" suspending a utensil from function. Furthermore, he cites the opinion of the Rema who classifies Tefilin as Kli She’melachto L’heter-a utensil designated for permissible activity. He holds that there is no prohibition wearing Tefilin on Shabbat for reasons other than the Misva, such a protection from Mazikim (evil spirits). By relying on the combination of these two minority opinions, Hacham Ovadia permits removing the Tallit from the Kuracha.
While Tefilin may not be worn on Shabbat, they may be moved if their place is needed or for use in an educational demonstration. One may carry a Kuracha contacting Tefilin and Tallit, and may remove the Tallit form the Kuracha.