A neighbor of a yet-to-be built Oak Bluffs inn is suing the town planning board, arguing the board’s approval of the inn’s permits ignored town parking requirements.

Rita Bartolomeu, a Medford resident who owns property on Narragansett avenue in Oak Bluffs, filed a lawsuit in the state Land Court Tuesday against the planning board and the owners of the abutting Four Sisters Inn. She contends the board shouldn’t have approved the inn’s special permit because the bed and breakfast doesn’t have enough off-street parking spaces and the one it does have isn’t large enough.

Oak Bluffs planning board chairman Ewell Hopkins said that Ms. Bartolomeu’s legal fight could have wide-ranging effects on the downtown area, where many businesses don’t have their own dedicated parking, if it gained favor in the courts.

Oak Bluffs currently allows businesses to pay annual fees in lieu of providing the required number of off-street parking. If that bylaw is challenged, it could have massive implications for Circuit avenue businesses, Mr. Hopkins said.

“This is a fundamental challenge to how we’re addressing vehicular congestion in our downtown,” he said. “It’s much more than a challenge to the applicant in question.”

Currently a vacant lot, Elizabeth and Henry Marshall last year proposed to build the four-bedroom inn with an innkeeper’s apartment on Narragansett avenue. The planning board approved the project this April, and said the owners could have only one parking spot if they made yearly payments in lieu of providing four additional off-street spaces.

The planning board ruled that the parking payments were allowed under the town’s bylaws, which lets businesses that can’t meet parking requirements pay $100 per spot annually.

But Ms. Bartolomeu claims the board exceeded its authority and the project should have been required to have five off-street spaces, or at a minimum, get a waiver for five spaces.

“Instead of proposing to construct an ‘inn’ that meets off-street zoning requirements, the Marshalls’ proposed project attempts to maximize the size of the structure on the property to the detriment of other amenities that would serve the community, such as off-street parking,” Ms. Bartolomeu’s attorney wrote in the 17-page complaint.

The town’s bylaws, according to the suit, require the off-street parking spot be 9 feet by 18 feet, but the plans submitted show the only onsite parking at the Four Sisters to be 9.3 feet by 16 feet.

The project never got any zoning relief from meeting the minimum requirement, according to Ms. Bartolomeu, and the business should have needed a waiver for that fifth spot as well.

Ms. Bartolomeu, who raised parking and other concerns about the project during the local permitting process, is now calling for the state land court to annul the planning board’s decision.

The town has not officially responded to the case in court and a further hearing has not yet been set.