One does not have to be a supporter of labor unions or of everything they do to question the “right to work” rhetoric animating new laws in Michigan and elsewhere that seek to defund unions.

A “right to work” is not at stake. Since 1947, it has been unlawful for private employers and unions to require workers to join a union to obtain a job; and the same applies in government offices as well. It is also unlawful to require workers to become full-fledged members of a union to keep a job. All that can be required is what the U.S. Supreme Court in a 1963 decision called “financial core membership,” which is solely the obligation to pay the reasonable costs of union representation. It is also well-established constitutional law that no part of these “financial core” dues may be used to fund the partisan political activity of unions.

What is at stake is the union’s right to be paid for its services in those shops where a majority of workers have chosen union representation. The type of clause outlawed by the new Michigan law, often called a “union security” or “union shop” clause, requires workers to pay dues after their 30th day of employment. Workers obtain and keep their jobs without regard to their union status or preferences; their sole obligation is to pay dues after they have been hired.

Unions need such a clause to stay in business because they negotiate “collective goods” — improved wages and conditions that extend to all workers in the unit, not just union members or those who paid their dues. For most of what a union tries to do — secure higher wages, better hours, a safer worksite, lower costs for pensions and due process for disciplined workers — there is no feasible way for the union to limit negotiated improvements to those who pay dues. Indeed, the Supreme Court held in the 1940s that whenever a union obtains authority to negotiate on behalf of a group of workers, it has a corresponding legal duty to represent fairly all within that group, whether they are supporters or opponents of the union.

A “fee for service” concept cannot work when services are and, under the law, must be provided to all whether they are willing to pay the fee for not. Try getting citizens to cough up the cost of a subway or bus ride after they have completed the ride, or to pay the costs of fire protection after the fire department has put out the blaze in their home or business.

There are many reasons why some sunbelt states attract new industry, including the cost of land, attractive tax incentives, government investment in infrastructure and the attitude of the people. It is doubtful, as some commentators have suggested, that companies pick these states to site new facilities principally because unions cannot be paid for their services.

When opponents insist on a right to free ride on union representation, they have seized the rhetorical high ground of liberty and job growth to conceal a more prosaic, and often politically partisan, motive — to deprive unions of a justifiable funding mechanism so that they no longer can play a useful collective-bargaining role in our society.

Samuel Estreicher is Dwight D. Opperman Professor of labor and employment law and director of the Center for Labor and Employment Law at New York University.