If a person is walking outside on Shabbos, and with his head/ hat he brushes against a tree branch or against the leaves of a tree that hang low, thereby jostling them/ causing them to move, is this a problem?
Answer:
There is no problem with this.
Moving muktzeh items inadvertently in the course of one walking poses no problem according to all opinions. There is also no concern for removing leaves, as that is not one’s intent and it is only a possible outcome of walking there.
