Accidental Carrying on Shabbat
What do you do if you realize you’re carrying something outside on Shabbat, such as if you have something in your pocket you didn’t know about?
The Aish Rabbi Replies
It’s a good issue. In fact, one must know this law well because our natural reaction in such a situation is to stop short, but as we’ll see in a moment that would make this law even more problematic.
One of the forbidden types of labor on Shabbat is carrying. This includes both carrying from a private domain to a public domain (or vice versa) and carrying 4 cubits within a public domain. To fully transgress any of these, on a Torah level, one must pick up the item in the first domain and place it down in the second. Standing still (after you had been walking) is the equivalent of putting the item down. Thus, if you are walking outside and notice that something is in your pocket, you have not fully transgressed carrying on Shabbat so long as you have not stopped walking. (Similarly, even if you did stop earlier while walking outside, to now transgress the act of carrying 4 cubits in public you would have to stop again.)
Another relevant principle in Jewish law is that if one does a forbidden act on Shabbat in an unusual manner, it will generally be forbidden only rabbinically, and not from Torah law.
Based on the above, the first thing to know when this happens to you is that you must not stop walking. If you stop, then you have certainly transgressed a Torah law. Rather you should keep moving, but as soon as possible and while still walking, you should drop the item in an unusual manner – such as by shaking your pocket and letting it fall out. This way you will transgress only a rabbinical prohibition: you never stopped walking so the item was not “put down” through your standing, and you instead deliberately put it down in an unusual manner.
If the item is valuable and you don’t want to drop it in public, you can keep moving and take it back to your house or another private domain and drop it in an unusual manner. In such a case, however, it is not sufficient to walk. You need to run (or move in an unusually quick manner) – to serve as a reminder for yourself that you may not stop moving in public while you have the item. In addition, this option is only permitted if you had never stopped walking at all while you were outside, and you can reach a private area without having to pause at all, even to enter the private domain.
If the item is valuable and you have stopped already, then you can carry it by starting and stopping, moving less than 4 cubits (6-7 feet) at a time, preferably putting down the item every time you stop. Then when you reach your house, you should drop it in an unusual manner.
(Sources: Shulchan Aruch O.C. 266:7,11-12, Mishna Berurah 18,31,36, Shemirat Shabbat K’Hilchata 18:52 with note 233, Orchot Shabbat 28:71.)