Final answer:
The presence of a labor union empowers workers in negotiations by leveraging collective bargaining, though it can sometimes result in fewer union workers being hired. Employers naturally have more bargaining power, and employee rights are protected by specific laws. American union membership has been declining over the long term.
Step-by-step explanation:
The presence of a labor union changes negotiations between employers and workers primarily by empowering workers. Labor unions serve as collective bargaining agents for their members, leveraging the strength of the group to negotiate better wages, benefits, and working conditions. When a union represents workers, it can act akin to a monopoly over the labor supply, requiring employers who need workers to meet the union's demands. This group negotiating can lead to higher pay and sometimes better job security for union members. However, it is important to note that higher union wages might also result in employers hiring fewer union workers than they otherwise would, which can be an adverse effect for the overall employment levels.
Employers naturally have an advantage in bargaining with individual employees due to their greater resources and the individual's need for employment. Laws such as the National Labor Relations Act and the Fair Labor Standards Act work to protect employee rights and level the playing field. The long-term trend in American union membership has seen a decline, influenced by factors such as the rise of service industries, globalization, worker-friendly legislation, and laws unfavorable to union organizing.