LANSING (AP) – The Michigan Supreme Court is hearing arguments in a case that will determine whether state workers are covered by a right-to-work law.

The law says public and private workers in Michigan can’t be forced to pay union fees as a condition of having a job. The dispute at the state’s highest court Tuesday centers on whether the law steps on the turf of the Civil Service Commission.

READ MORE: Michigan Gov. Whitmer Tests Positive For COVID-19, Reports 'Mild Symptoms'

Unions say the state Constitution puts the commission solely in charge of labor matters affecting state employees.

But in August, in a 2-1 decision, the appeals court said the law applies to 35,000 state workers. In response, the commission says the court “invented a new rule of law.”

READ MORE: Trump Says Mar-a-Lago Was 'Raided' By FBI

Unions have much to lose if the decision stands.

MORE: Michigan Passes Controversial Right-To-Work Law

Right To Work: Just The Facts

MORE NEWS: Lighthouse Partners With Gleaners To Expand Food Relief

© Copyright 2015 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.