Question: Is it permissible to open the canopy attached to the top of a baby stroller on Shabbat?
Answer: One of the thirty-nine forbidden works on Shabbat is building. Included in the forbidden work of building is the prohibition to creating a tent or awning on Shabbat. Making a permanent tent on Shabbat is a Torah prohibition. Making a temporary tent or awning on Shabbat, however, is prohibited by virtue of a rabbinic injunction. Just as it is forbidden to make a tent on Shabbat, it is likewise forbidden to demolish or take down a tent on Shabbat.
It would seem that a canopy attached to a baby stroller, which is meant to shade the baby from the sun, rain, and the like, should be considered like an actual tent and it will be forbidden to open it on Shabbat due to the prohibition of making a tent.
Indeed, in earlier generations (until approximately seventy years ago), the more affluent Jews in the city of Baghdad would raise deer in the courtyards of their homes. The Gemara (Eruvin 102a) states that Rav Huna had such deer in his possession. These deer would need shade during the daylight hours and fresh air during the night. During the rest of the week, they would spread a mat over the courtyard during the day to shade the deer from the hot sun and during the night, they would roll the mat back so that they would have fresh air. Rav Huna therefore asked Rav if he could continue to do so on Shabbat.
Rav replied that when he rolls back the mat at night, he should leave an area of a “Tefach” (approximately 3.1 inches) unrolled. Then, on Shabbat morning, he would be able to unroll the mat again to protect the deer from the sun. (The Tefach that must be left open is besides for the part of the mat that is rolled up.)
We see from here that a tent or awning that was opened before Shabbat to at least the area of a Tefach may be opened even more on Shabbat since adding onto a pre-existing tent or awning is permissible. The Rambam (Chapter 22of Hilchot Shabbat, Halacha 27) and Maran Ha’Shulchan Aruch (Chapter 315, Section 2).
Thus, Maran Rabbeinu Ovadia Yosef zt”l rules that the foldable canopy on top of a baby stroller should be opened before the onset of Shabbat the amount of a Tefach and in this way, it will be permissible to open it all the way on Shabbat, as this is exactly the law of adding onto a pre-existing awning on Shabbat which the Gemara permits.
Although Hagaon Chazon Ish (Chapter 52, Section 6) rules completely leniently in this regard since the canopy is always attached to the stroller and it therefore resembles a door which is constantly opened and closed on Shabbat and a folding chair, which may be opened as usual on Shabbat, nevertheless, since many great Acharonim disagree with the Chazon Ish’s opinion on this matter and bring several proofs that a stroller’s canopy is not comparable to a chair and door, it is therefore halachically preferable to follow the ruling of Maran zt”l and leave at least one Tefach of the canopy open before the onset of Shabbat and in this manner, it will be permissible to open it completely on Shabbat. (Chazon Ovadia-Shabbat, Volume 5, page 302)