A more thorough explanation:

Definition: Hot cargo refers to goods that are produced or handled by an employer with whom a union has a dispute.

For example, if a union is in a dispute with a company that produces clothing, any clothing produced by that company would be considered hot cargo. If the union members refuse to handle or transport the clothing, it can cause a disruption in the company's operations.

This term is often used in labor law to refer to situations where a union is trying to put pressure on an employer to meet their demands. By refusing to handle or transport hot cargo, union members can cause financial losses for the company and force them to negotiate with the union.