Mass-Action Theory Law and Legal Definition

Mass action theory refers to a principle that as long as a labor union is functioning as a union it must be held responsible for the mass action of its members. In short, as long as a labor union is functioning, it is vicariously liable for the joint acts of its members. The rationale for this theory is that large groups of men do not act collectively without leadership and that a functioning union must be held responsible for the mass action of its members.