Original sentence: Proponents such as the Mackinac Center for Public Policy contend that it is unfair that unions can require new and existing employees to either join the union or pay fees for collective bargaining expenses as a condition of employment under union security agreement contracts
Edited sentence: Proponents such as the Mackinac Center for Public Policy contend that it is unfair that unions can require new and existing employees to either join the union or pay fair share fees for collective bargaining expenses as a condition of employment under union security agreement contracts