It bars pension benefits from being "diminished or impaired".
Some states, including Illinois, have constitutions saying that public-sector pensions cannot be diminished or impaired.
Some legal experts say the plan would violate the Illinois Constitution, which says pension benefits "shall not be diminished or impaired".
Labor leaders have objected to two formal proposals being considered, questioning whether they violate a provision of the state Constitution barring pensions from being diminished or impaired.
What Michigan's Constitution actually provides is that pension benefits "shall be a contractual obligation thereof which shall not be diminished or impaired thereby".
Unions are naturally opposed to any attempt to water down pension obligations, and point to a promise in the state's constitution that the benefits of pensions cannot be diminished or impaired.
His plan is being fought vigorously by unions that point out that pensions are protected by Michigan's Constitution, which calls them a contractual obligation that "shall not be diminished or impaired".
By giving workers choices and focusing on contributions rather than on benefit cuts, the bill's supporters hope to comply with a clause in the State Constitution that defines a pension as a contractual commitment, "the benefits of which shall not be diminished or impaired".
The constitutions of seven states -- New York, Illinois, Louisiana, Michigan, Alaska, Arizona and Hawaii -- say pension benefits cannot be "diminished or impaired".
However, according to the state constitution, pension and retirement rights are considered a "contractual relationship, the benefits of which shall not be diminished or impaired".
