Hawaii County groups that say their island deserves a fourth seat in the state Senate based on population growth during the past decade have 45 days to challenge the matter in court.

The groups are challenging the constitutionality of new maps for the state’s political boundaries approved Monday by the state Reapportionment Commission. They say the plan is based on a population count that includes too many nonpermanent residents, such as military members and students.

"I have spoken with my clients, and we are ready to proceed," said Hawaii island attorney Stanley Roehrig, a former state representative. "We’re going to file a petition to review this matter."

The petition, on behalf of state Sen. Malama Solomon (D, Hilo-Honokaa) and members of the Hawaii County Committee of the state Democratic Party, would be filed with the state Supreme Court.

Roehrig said he was working on a timetable for when the challenge would be filed.

The lawsuit would challenge the commission’s decision to exclude only about 16,000 nonresident military members and students based on their known residency status and the ability to locate them from the available data.

Although the commission said it was able to perform similar extractions on up to 64,000 additional nonresident military and students, the accuracy in those cases was not as certain, and those people were left in the population count.

Changes in privacy laws have made it impossible to locate and extract nonresidents from their census blocks — the units used for drawing up districts — to the same degree as in previous years, officials said.

Keeping the so-called nonresidents in the population base negates growth on Hawaii County that normally would result in Hawaii island gaining a fourth seat in the state Senate. Oahu would lose a seat.

"I really think the Big Island deserves a Senate seat," said Commissioner Anthony Takitani, a Maui attorney and the only commission member from a neighbor island. "The way I read the constitution, I don’t think it’ll stand, but we’ll see."

Commission Chairwoman Victoria Marks, a retired circuit judge, has argued that members did the best they could with the information available.

"It’s all a question of how accurate is the data that you get from the military, and right now it isn’t that accurate," Marks said.

Roehrig, among others, has argued that the nonresidents, regardless of their exact address, should be taken off the total population count from the beginning, before allocating the number of House and Senate seats to each county.

"That’s only the first step," Marks countered. "You don’t have the location, so what districts do you take the people out of? It’s not as simple as some might make it seem, so we’ve done the best we can and that’s all we can do."

The commission also approved staggered terms for 12 of the 25 state Senate seats, based on a mathematical formula.

Based on the new maps, three pairs of incumbents in the House would wind up in the same districts and be forced to run against each other.

On Oahu, Rep. Kymberly Pine (R, Ewa Beach-Iroquois Point) would face Rida Cabanilla (D, Waipahu-Ewa), and Rep. Barbara Marumoto (R, Kalani Valley-Diamond Head) would face Rep. Mark Hashem (D, Hahaione Valley-Aina Haina). New boundaries also would pit two Hawaii island Democrats against each other: Jerry Chang (D, Piihonua-Kaumana) and Mark Nakashima (D, Hawi-Hilo).

The state Office of Elections must publish the new maps by Oct. 10.