By issuing an executive order this week ending the requirement that state employees who choose not to join a union pay fees to support their share of collective-bargaining costs, Illinois Gov. Bruce Rauner is the latest elected official to thrust the politically charged debate over public-employee unions into the headlines. Rauner calls the fees a "critical cog in the corrupt bargain that is crushing taxpayers." If his order withstands the expected legal challenges, it would likely cripple Illinois' public-employee unions.

The issue the new Republican governor's order addresses comes down to balancing the First Amendment rights of employees not to support political activity they disapprove of against preventing "free-riders" from reaping benefits from collective-bargaining agreements toward which they didn't contribute.

But politics makes this already delicate balance infinitely more complex. Illinois law allows public employees to decline to join a union and prohibits the "fair share" fees non-members pay to cover unions' collective-bargaining costs from being used to fund political activity. Rauner contends that it's nearly impossible to draw a distinction between the two.

Too many unions laughably claim that none or almost none of their dues revenue supports political activity. Rauner is right about the difficulty of untangling bargaining and political expenditures.

Few states illustrate that reality better than Massachusetts, where during the 2011-12 election cycle (the last for which data are available) 18 of the 20 political action committees that gave the most to candidates for state and county offices were affiliated with labor organizations. The result is negotiations in which elected officials bargain with their benefactors.

As a result, taxpayers too often are left out in the cold. Among the changes pushed through by Wisconsin Gov. Scott Walker when that state faced a projected $3.6 billion deficit in 2011 was eliminating employee benefits as a topic for collective bargaining. The Boston area's Massachusetts Bay Transportation Authority provides an example of why the provision is so important. One reason the MBTA is a financial basket case is its out-of-control pension costs. Unlike for Massachusetts state employees, MBTA workers' pension contributions are subject to collective bargaining. As a result, MBTA workers contribute far less than their state counterparts, forcing the authority to pick up the rest.

Walker's changes didn't stop with taking benefits out of the collective-bargaining arena. They included a draconian provision that requires public unions to be recertified annually. Other states also have been unnecessarily harsh in their attacks against public-employee unions. In Indiana in 2005, for example, then-governor Mitch Daniels issued an executive order that ended collective bargaining for state employees.

In the end, the best that state and local leaders can do is try to strike a serviceable balance between worker rights and taxpayer interests. Allowing workers to contribute nothing toward the cost of negotiating collective-bargaining agreements from which they benefit would unfairly tip that balance against public employees.