This is the ordinance referenced, I believe:
Sec. 13-21. - Illegal possession of a firearm.
(a)
It shall be unlawful for any person to carry or possess on his person, whether concealed or not, any pistol, handgun, rifle, shotgun or other firearm. Provided, however, that the provisions of this section shall not apply to any law enforcement official engaged in the exercise of his official duties; nor shall it apply if the person possessing or carrying the firearm is located within the structural confines of his residence or business establishment.
(b)
It shall be an affirmative defense to the prosecution of this section if the firearm is secured by a key-operated trigger-locking mechanism or if the firearm is disassembled to an extent that it is clearly evident that the firearm is nonoperational.
From what I understand, Louisiana has state preemption of firearms laws, except for local laws passed before July 15, 1985.
The above ordinance appears to have been passed 7-15-86 and therefore may in fact be in violation of
§1796. Preemption of state law.
PART II-A. MISCELLANEOUS PROVISIONS
§1796. Preemption of state law
A. No governing authority of a political subdivision shall enact after July 15, 1985, any ordinance or regulation more restrictive than state law concerning in any way the sale, purchase, possession, ownership, transfer, transportation, license, or registration of firearms, ammunition, or components of firearms or ammunition; however, this Section shall not apply to the levy and collection of sales and use taxes, license fees and taxes and permit fees, nor shall it affect the authority of political subdivisions to prohibit the possession of a weapon or firearm in certain commercial establishments and public buildings.
B. Nothing in this Section shall prohibit a local governing authority in a high-risk area from developing a plan with federally licensed firearms manufacturers, dealers, or importers to secure the inventory of firearms and ammunition of those licensees in order to prevent looting of the licensee's premises during a declared state of emergency or disaster. Such plan shall be renewed on a periodic basis. The information contained in the plan shall be deemed security procedures as defined in R.S. 44:3.1 and shall be released only to the sheriffs of the parishes or police chiefs of municipalities in which the declared state of emergency or disaster exists.
C. For the purposes of this Section:
(1) "Declared emergency or disaster" means an emergency or disaster declared by the governor or parish president pursuant to the provisions of the Louisiana Homeland Security and Emergency Assistance and Disaster Act.
(2) "High-risk area" means the parishes of Assumption, Calcasieu, Cameron, Iberia, Jefferson, Lafourche, Orleans, Plaquemines, St. Bernard, St. Charles, St. James, St. John, St. Martin, St. Mary, St. Tammany, Tangipahoa, Terrebonne, and Vermilion.
Added by Acts 1985, No. 741, §1, eff. July 17, 1985; Acts 2006, No. 254, §1.