Terry Jones, a Founders Professor of political science, discussed the issue of preemption as played out in the fight over a higher minimum wage ordinance in the city of St. Louis Sunday night on PBS Weekend NewsHour.

A segment on PBS Weekend NewsHour Sunday evening explored the growing tension over policy decisions in American cities, many of which are led by Democrats but exist in states with legislatures increasingly controlled by the Republican Party.

In Missouri, it’s recently been playing out over the issue of the minimum wage.

The Board of Aldermen passed an ordinance in 2015 that would have raised the minimum wage in the city of St. Louis incrementally from a rate of $7.65 per hour at the time to $11 by January 2018.

A court ruling initially blocked the ordinance from being implemented, but the Missouri Supreme Court overturned that decision in February and upheld the higher minimum wage. But Republicans responded by moving to fast-track legislation that could block it once more by what is known as preemption.

“Preemption is when a higher level of government tells a lower of government, ‘You can’t do that,’ or ‘You have to do it,’” Terry Jones, a Founders Professor of political science at the University of Missouri–St. Louis, told special correspondent Chris Bury during Sunday’s broadcast.

As Jones explained, the practice of preemption in Missouri and many other states really began with battles over gun control legislation in the 1980s and 1990s.

“It’s very forthright,” he said. “It says everything dealing with guns are only the purview, legally, of the state legislature and the governor. Local communities cannot pass any kind of separate control for regulations dealing with firearms.”

Preemption also has occurred in debates over regulations on things such as plastic grocery bags, pesticides, e-cigarettes and sugary drinks in other parts of the country.

“As a policy tool, preemption has been used primarily by the Republican Party, but even that is a bit of an oversimplification because it’s been at the urging of interest groups that are allied with the Republican Party,” Jones said. “Those forces that want to fight the minimum wage find it very difficult to carry on that struggle in a progressive, highly Democratic community like a Kansas City or the city of St. Louis.”

Sunday’s report was part of an ongoing series called “Chasing the Dream,” which reports on issues of poverty and opportunity in America.

Watch Sunday’s report or read a transcript here.