The Faubourg Marigny Improvement Association is seeking to block a provision in the city’s new zoning law that would allow taller residential buildings along the riverfront in that neighborhood.

In a lawsuit filed Thursday in Civil District Court, the association said the provision would cause “severe changes” to the Marigny neighborhood and should be declared null and void because it did not go through a hearing process with the City Planning Commission.

The lawsuit, which seeks a declaratory judgment and permanent injunction, names the city of New Orleans, the City Council and the City Planning Commission as defendants. It was assigned to Judge Kern Reese.

The suit takes issue with an amendment to the city’s recently adopted comprehensive zoning ordinance, which was unanimously approved by the City Council this month after seven hours of discussion and about three dozen last-minute amendments.

The specific change at issue, requested by Mayor Mitch Landrieu, modified one of the most contentious features of the new ordinance: the creation of an “overlay district” along the riverfront.

The district was opposed by some residents of Bywater, Marigny and the French Quarter because it would allow structures to qualify for a 25-foot “height bonus” — bringing a residential building’s maximum height to 75 feet — if the building’s design incorporates elements such as open space, public plazas and open-air cafes with visual access to the river, or if the developer agrees to pay for at least half the cost — not less than $250,000 — of a new bridge over the floodwall, a railroad crossing or other capital improvement that “significantly increases” public access to the riverfront.

As approved by the council, the overlay district also includes part of the Algiers Point riverfront, but an Uptown section between the Pontchartrain Expressway and Jackson Avenue was removed.

Marigny residents had succeeded in carving their neighborhood out of the district in the final draft of the proposed CZO, meaning residential buildings along the riverfront in that neighborhood would not have been eligible for the height bonus, but the Landrieu-backed amendment put the neighborhood back in.

The amendment also increased, from 5 percent to 10 percent, the percentage of affordable housing units required for new residential buildings in the district that would receive the height bonus.

The City Council unanimously approved the amendment.

The lawsuit contends that under the City Charter, the amendment should first have gone to the City Planning Commission for a recommendation and public comment before being folded into the zoning document, which has been in preparation for several years. Because it did not go through that process, the amendment should be declared null and void, the lawsuit says.

A spokesman for Landrieu said the proposed change was filed and posted to the City Council’s website in April. It was part of a much broader amendment that included changes to a wide variety of sections in the CZO. The part of the overall amendment dealing specifically with the overlay district was separated for the final vote “to allow the council to consider the issue separately from the other non-controversial amendments,” Landrieu spokesman Brad Howard said.

The lawsuit also says the amendment violates the city’s master plan because it “gives developers — as a matter of right — the ability to exceed existing height and density requirements, including in the Faubourg Marigny.”

The new CZO is intended to give legal force to the guidelines and principles set forth in the city’s master plan for long-term development. It governs development on all property in New Orleans and includes lists of permitted land uses for each zoning classification, as well as height limits, building sizes, setback requirements, urban design standards, operational rules and other regulations.

Landrieu has yet to sign the ordinance into law. Howard said the mayor hasn’t received the final document yet because the City Planning Commission staff and the City Council’s clerk’s office still are incorporating into it all of the amendments passed by the council.