Shoppers might soon discover that the grocery store is less expensive and more convenient.

Two weeks ago, the Texas Supreme Court heard oral arguments in a case questioning the legitimacy of municipal bans on plastic bags. If justices reaffirm an appellate court ruling, consumers will be unburdened from this clear example of government overreach.

At issue in the case of Laredo Merchants Association v. the City of Laredo is whether the city’s bag ban — and all others by extension — is allowed under state law. A plain text reading of the law leaves no doubt that it is not.

Texas’ Health and Safety Code is fairly straightforward, stating, “A local government or other political subdivision may not adopt an ordinance, rule, or regulation to … prohibit or restrict, for solid waste management purposes, the sale or use of a container or package in a manner not authorized by state law.”

That’s about as direct as it gets. Cities can’t ban plastic bags for trash-related reasons. But officials have tried to get around the law by performing a sort of mental gymnastics, arguing against the common understanding of words and intent.

For example, one of the city’s arguments is that a plastic bag isn’t a container or a package. But the dictionary disagrees.

Webster’s dictionary defines the word “bag” as a “container that may be closed for holding, storing, or carrying something” and the Oxford dictionary defines it to mean “a flexible container with an opening at the top.”

This common understanding of bag is also shared by the 4th Court of Appeals, the Texas attorney general’s office and numerous other interested parties. Hence, to argue that a bag is not a container takes more imagination than not.

Another of the city’s arguments is that the bag ban ordinance was not passed for solid waste management purposes, which is expressly prohibited by state law.

“In the ordinance, never anywhere in the drafts (was there) anything about solid waste management. It was always about beautification and flood control,” said Tricia Cortez, executive director of the Rio Grande International Study Center, one of the special interest groups behind the original ordinance.

But the city’s own documentation says otherwise.

In an official decree dated Aug. 19, 2013, all of the City Council’s past actions are recorded and the first one listed is: “Council made motion on October 15, 2007 for Citizens’ Environmental Advisory Committee (CEAC) to develop ordinance to deal with the litter problem from plastic checkout bags.”

From the start, the ordinance has had its roots in an environmentalist push “to deal with the litter problem,” and that’s a problem. Cities can’t pass local laws banning the generation of litter. That falls under the scope of solid waste management, and that’s not allowed by state law.

Considering the arguments, it’s clear that the city’s case doesn’t hold up. And if the Supreme Court finds the same, then it will mean a return of plastic shopping bags. But it will also mean something much more — a restoration of the rule of law.

See, Laredo isn’t the only city probably violating the law. A number of Texas cities, including Austin, Fort Stockton and Port Aransas, have adopted similar restrictions against sound advice. Those chickens could come home to roost, and rightfully so.

Cities can’t pick and choose which laws to follow, no matter how noble their intentions or how much they want to save the planet. We are a nation of laws and not of men or of social causes.

That’s a principle that needs to be reinforced with a favorable decision from the Texas Supreme Court. Once that happens, Texans will have struck a blow for order and convenience.