Attorneys general in 10 states are moving to investigate whether a clause in fast-food franchise agreements is preventing workers from switching jobs, locking them into low-paying positions and, some economists say, contributing to widespread wage stagnation in the United States.

In a letter released publicly on Monday, attorneys general from California, Massachusetts, New York, seven other states and Washington, D.C., asked eight restaurant chains for information about whether their contracts with franchisees prohibited them from hiring workers away from one another. Arby’s, Burger King and Wendy’s were among the chains.

The restrictions, often referred to as no-poach clauses, do not stop workers from switching from, say, an Arby’s store to a Wendy’s, but can keep an employee of one Arby’s location from taking a job at another.

Although many types of franchise businesses impose such clauses, they may be most common in the restaurant industry, one of the largest employers in the United States. The fast-food sector, in particular, relies overwhelmingly on independently owned and operated franchise stores.