Barnacle parking devices, an increasingly popular alternative to parking boots that attach to car windshields and are designed to immobilize parked vehicles, are not allowed on public property, according to a statement from the Honolulu City Council last week.

The devices have been popping up increasingly in Kailua over the past few weeks and gained attention on social media. They attach to car windshields through suction cups and force drivers to pay a fine to release the device. They are not allowed to be used on vehicles parked on public property, which includes public roads, public easements and unimproved sidewalks, according to City Council Vice Chair Esther Kia‘aina.

Pono Parking, a private company, is the “exclusive provider and operator” of barnacle property devices on Oahu, according to its website. The company contracts with small businesses, landlords and property managers to enforce parking regulations.

Pono Parking President Keoki Anderson said in an email that the company does not operate on public property, and only on private commercial properties.

“We’ve never enforced on a public road or anything. We only do private properties,” Adam Yamamoto, Anderson’s assistant, said. “There was a controversy about one property in Kailua that we were enforcing for. Some people from the city say it’s a public easement, other departments say it’s not, others say it’s an unimproved sidewalk, so we decided to not enforce anymore for residential properties.”

Yamamoto said Pono Parking does enforcement for almost all of the properties they contract with. Charges to remove the barnacle parking device from vehicle windshields can vary depending on the property owner.

“It was residents who had asked the company to put (the devices) on, and they had no authority to do that, but the company should know better,” Kia‘aina said. “Determining whether (the parking) is legal or illegal, that’s not their job. Even if something was illegal, that’s still not their job.”

Kia‘aina said she’s been in contact with the Honolulu Police Department, which said the placement of barnacle parking devices on vehicles either partially or completely on public property could be considered second-degree criminal tampering.

Yamamoto said HPD called Pono Parking and notified the company that the barnacle parking devices could not be used on public property.

Kia‘aina said if people see a barnacle placed on their vehicle, they should call HPD immediately.

“A lot of people don’t like cars parked in front of their homes, but they’re not taking the law into their own hands and having a private company put that barnacle on,” Kia‘aina said. “I’m optimistic that the community responded. There was outrage because of the social media on this, and that shouldn’t happen.”

Parking boots were banned by state law in 2013, and are punishable by a fine of $100 for each offense. It is not explicitly stated in the law whether barnacle devices are legal or illegal in the state.

“We have a clear precedent that this type of activity or business is not permissible on Oahu, or anywhere in Hawaii for that matter,” City Council Chair Tommy Waters said in a statement announcing the Council’s position. “While a barnacle may be a different way to immobilize a car than a boot, it is exactly the same concept, poses the same potential for property damage, and is completely unregulated.”

Yamamoto said Pono Parking wants to see more regulation of unwanted parking on property lines.

“We want the conversation to start, for sure,” he said. “There’s a lot of confusion for people who live in Kailua and Lanikai and other places on ‘Can people park on my property line?’ Is it a utility easement or an unimproved sidewalk? We believe it is something that the city or state should clarify for those residents. Particularly for those in Kailua, along the whole property line, there would be cars parked all along the property.”

Additionally, the company believes the barnacle parking device is a “much more compassionate alternative” to towing.

“It’s much more environmentally friendly and doesn’t ruin your day,” Yama­moto said. “With towing there’s no forgiveness, and we’re surprised more people aren’t talking about the horrors of when you get your car towed. It’s not a fun thing. If you get barnacled because you’ve parked overnight somewhere that you weren’t supposed to, you pay and you’re on your way.”