Because farm laborers in the United States are not covered by the Wagner Act, the United Farm Workers union has been able to legally use secondary boycotting of grocery store chains as an aid to their strikes against California agribusinesses and to their primary boycotts of California grapes, lettuce and wine. The UFW's secondary boycotts involved asking consumers to stop shopping at a grocery store chain until such time as the chain stopped carrying the boycotted grapes or lettuce or wine.
Secondary boycotting is frequently confused with secondary striking, which is also a prohibited tactic for those labor unions covered by the Taft-Hartley Act. Some legal definitions for secondary boycotting divide it into two different kinds, secondary consumer boycotts as per the above definition of secondary boycotts, and secondary employee boycotts, also defined as a secondary strike.
In competition law, a group boycott is a type of secondary boycott which involves several competitors in a market attempting to shut another competitor out of a relevant market by agreeing not to do business with any of the customers of the firm they are attempting to shut out.