The Outdoor Circle and other guardians of Hawai'i's scenic beauty want the state Legislature to outlaw paid advertising on cars, trucks and buses, which they see as another clever move to dodge the state's ban on billboards.

The proposed ban would not apply to companies that advertise on their own vehicles, as with Polynesian Cultural Center buses or Budweiser beer delivery trucks. It also would not restrict political speech — such as the truck that displays graphic images of aborted fetuses — because it is protected by the First Amendment to the U.S. Constitution.

But it would prohibit companies from paying others to market commercial messages or display logos on their vehicles. The ban would cover advertising trucks, which have been seen in Honolulu, that scroll commercial messages from different companies or groups. It also would cover signs, such as restaurant ads, that are placed for money on buses or trolleys, and what are known among advertisers as "car wraps."

"The idea is to stop this problem before it gets out of hand like it has on the Mainland," said Bob Loy, director of environmental programs at the Outdoor Circle.

While some may view the proposed ban as an overreaction, Loy said people forget that King Street was once lined with billboards and ads once fouled Diamond Head. "Hawai'i has done an outstanding job of protecting its scenic environment," he said.

Some who work with advertisers said they have mixed feelings. At least one company had ad trucks in Honolulu last year, but they have been taken off the streets, and other advertisers have not jumped into the market.

Byron Riddle, who is in sales and marketing at Fleet Street Graphics, which offers car wraps, said they can be expensive and usually are ordered by companies to promote products on their own vehicles.

"For the most part, it's people looking to advertise their own company," Riddle said. "But I can see how we don't want these on a zillion vehicles out there."

The state House and Senate are considering bills to ban the mobile advertising without intruding on other forms of protected speech. The Outdoor Circle was concerned enough about the language of the bills to hire Jon Van Dyke, a constitutional law professor at the University of Hawai'i-Manoa, as a consultant.

"We want to make absolutely certain it does not get into political speech," said Rep. Kirk Caldwell, D-24th (Manoa), who supports Outdoor Circle.

But Caldwell and other lawmakers are courting heartache in an election year with a separate bill that would regulate the size and placement of political yard-signs.

The bill would limit signs to 4 feet by 2 feet, with a maximum of 16 square feet for all signs on a property. The signs would have to be either 15 feet back from the road or attached to a building. Residents would be barred from accepting any payment for displaying a sign.

Some lawmakers decided a bill was necessary after the proliferation of large signs during the 2004 Honolulu mayor's race between Mufi Hannemann and Duke Bainum, including some competing Hannemann and Bainum signs on the same property.

"We're so proud of not having billboards, but during political campaign time, we just go berserk," said Rep. Sylvia Luke, D-26th (Punchbowl, Pacific Heights, Nu'uanu Valley), the chairwoman of the House Judiciary Committee.

Reach Derrick DePledge at ddepledge@honoluluadvertiser.com.