585. Destructive Labor

Shabbos 1:16

If one person cannot perform an act of labor by himself so that another person's involvement is necessary, all the participants in the act are liable. For example, if two people transported a beam from the private to the public domain, both are liable because neither one of them could have performed this labor alone and they performed it together from the start to finish. The smallest amount of work for which a team would be liable is the same as for when one person performs a given labor. If one of them is strong enough to carry the beam alone but the other would need help, then when they carry it together, the one who could have done so alone is liable and the one who could not is considered an assistant. One who only assists in performing an act of labor is not liable. This is true in all comparable situations.

Shabbos 1:17

If one performs an act of labor destructively (as opposed to constructively), he is not liable. For example, if one person injures another person or an animal with destructive intentions, or if he tears or burns clothes, or if he breaks utensils with destructive intentions, he is not held liable. If a person dug a pit just because he needed the dirt (as opposed to the hole itself being useful), it is considered a destructive labor and he is exempt. Even though he performed an act of labor, he is not liable because his intention was destructive rather than constructive.