The Justice Department says six states have ended policies that grant in-state college tuition to illegal immigrants after legal action by the federal government. Kansas is the latest state to stop the benefit, joining Texas, Kentucky, Oklahoma, Nebraska and Illinois.

The DOJ argues that federal law prevents states from offering undocumented students lower tuition rates when the same rates are unavailable to U.S. citizens who live outside the state. Administration officials say the policies place noncitizens ahead of Americans and violate a restriction Congress enacted more than three decades ago.

The department has challenged similar laws across 21 states. Cases now remain active in 15 states, including Colorado, California, New York, Arizona, Maryland and Washington. The DOJ lost its case in Minnesota, but it is appealing that ruling before the 8th U.S. Circuit Court of Appeals.

The remaining lawsuits will determine whether other states must withdraw their programs or can continue offering resident tuition rates to undocumented students who attended local high schools or otherwise meet state eligibility requirements.

The legal battle is over the legality of states charging undocumented students less than American citizens who cross state lines to attend the same college. The DOJ argues this conflicts with federal law and gives people without legal status a taxpayer-supported advantage, while the states themselves maintain that locally educated students should qualify as residents regardless of status.

In-state tuition is often thousands of dollars cheaper each year, so losing it would likely prevent many undocumented students from enrolling, while also reserving state subsidies for citizens and legal residents.

The lawsuits will be a test of how much freedom states have to design education policy when Congress has imposed immigration restrictions. A DOJ victory would establish a precedent for challenging other state benefits offered to undocumented residents. With immigration a central theme for the upcoming midterms, Republicans can present these cases as a way to force equal treatment for U.S. citizens.

If Democrats address this issue ahead of the midterms, they will need to explain why residency should outweigh legal status when public money supports the discount.

The DOJ’s lawsuits could end the disparity in costs between undocumented students and U.S. students attending college out of state by requiring states to withdraw benefits that are not equally available to U.S. citizens.

Because public funding partly sustains in-state tuition, restricting it to citizens and lawful residents could also reduce the amount used to subsidize students without legal status. However, that does not guarantee lower tuition. State lawmakers and university boards would decide whether any savings reduce student costs, expand scholarships, or remain elsewhere in the budget.

Families should not expect tuition cuts when states end these programs. The change would be one of equal treatment: an American citizen would no longer be charged a higher public-college rate while an undocumented student receives the taxpayer-supported resident price because the citizen crossed a state border.