Arlington County is preparing to fight a legal challenge to its commercial sign ordinance — the first such challenge since the creation of the ordinance.

County Attorney Stephen MacIsaac says the county has a number of arguments to counter the lawsuit’s claims. The suit argues that regulators are infringing on a small business owner’s free speech by deeming a large mural painted on the side of her building a commercial sign and not artwork.

“I think it should be fairly apparent under the sign ordinance that this is a sign,” MacIsaac said. The mural is “clearly an effort to promote this woman’s business… to depict it as public art, I think, is a bit of a stretch.”

MacIsaaac said that the county’s sign ordinance is consistent with ordinances currently in place in other jurisdictions.

“Our sign ordinance is not unusual in any way,” he said. Arlington’s political sign rules were challenged just over 10 years ago, according to MacIsaac, but this is the first time someone has mounted a formal legal challenge to the commercial sign ordinance.

MacIsaac, the county government’s top legal counsel, added that the his office hasn’t officially been served notice of the suit, which was filed in federal court on Thursday. He expects the litigation to take about a year, and expected the county’s first court appearance to happen at some point this winter, perhaps February.

“We’re sort of in a wait and see mode right now,” MacIsaac said. “Right now we’re just assessing the case and waiting for the timeline to be established. This is going to be a process.”