A nearly yearlong ban on free travel for public school teachers who organize out-of-state field trips was overturned Friday after a Circuit Court judge invalidated advice given by the state Ethics Commission.

The Hawaii State Teachers Association, which represents 13,500 teachers, challenged the Ethics Commission opinion, arguing that the agency violated state law and the union’s constitutional rights when it said that under the state ethics code teachers cannot accept free travel from tour companies in exchange for organizing trips.

It had been a decades-long practice for teachers to travel free while chaperoning students on trips to the mainland and abroad, with a free chaperone spot typically provided for every six to 10 students booked.

The dispute over whether the practice is ethical dates back to spring 2015 when, in response to an inquiry, commission staff advised King Intermediate that a planned educational trip to Washington, D.C., and New York violated ethics laws. In that case, teachers selected and worked with a tour company to organize the trip, promoted it to students and then accepted a free ride and other benefits from the company.

The commission later warned teachers in an Aug. 4, 2015, memorandum that they could face sanctions under the ethics law if they accepted free travel on trips structured like King Intermediate’s. The commission then issued a more formal advisory opinion, explaining that such trips would violate ethics provisions against conflicts of interest and accepting gifts because the teachers would be receiving something of value from a private entity apparently in exchange for their official actions, and they would appear to be acting on behalf of the tour company.

“In short, because of the way the trips are currently organized and arranged, the state Ethics Code prohibits teachers from accepting free travel and other benefits from the tour companies,” the opinion concluded.

The advice, HSTA’s attorney said, had a “chilling effect” and resulted in a de facto ban on out-of-state trips because teachers were afraid of running afoul of the law. At least 31 trips were canceled during last school year, with many more halted before planning could start.

“No one wants to be found to be in violation of ethics, especially, in my experience, teachers — they are the example-setters,” Colleen Hanabusa, attorney for the teachers union, argued in court Friday.

She said teachers and the public were denied their due-process rights by the commission’s actions. “We are here because of the fact that we believe … that the Hawaii Supreme Court has made it very clear that agencies are not to act in any way that looks arbitrary and capricious,” Hanabusa said.

Judge Rhonda Nishimura ruled in favor of HSTA and voided the Ethics Commission’s memo and advisory opinion on the issue. She said the advisory opinion was rendered null and void under state law because it was issued after the statutorily allowed 30 days from the date advice was sought.

Nishimura also said that because the travel advice applies to a broader group, the process is subject to official rule-making under the law, which involves the public.

“So for the state Ethics Commission to issue such an advisory opinion and guidance memo that has a broader application than just a particular teacher or particular trip, does require that the entities involved engage in rule-making,” Nishimura said. She encouraged the parties “to engage in meaningful discourse” moving forward.

“The most critical part of rule-making is the ability to participate,” Hanabusa said, “as opposed to … a small group of lawyers or clerks within the Ethics Commission, who decide, ‘Oh, no, we don’t like this. And we believe that this, in our interpretation, is a prohibited gift.’ That’s not the law. And no one, as well intended as they may be, no one should have that kind of power over the general public.”

The commission, which was represented by Deputy Attorney General Robyn Chun, can appeal the ruling. Chun had argued that the commission’s advisory opinion did not amount to “rules” that would need to go through the rule-making process.

“The Ethics Commission has only issued advice and guidance,” Chun said. “No case has ever been filed for a violation of an advisory opinion, because they are not rules.”

The HSTA called the court decision a victory.

“Thousands of students were denied the great opportunity to learn beyond the classroom,” HSTA President Corey Rosenlee said after the ruling. “This was a victory today for the public school children of Hawaii. … For decades Hawaii has recognized that trips outside the classroom are invaluable, and this brings back sanity to the process and allows these kids … to experience the world.”

The decision could affect Board of Education guidelines that were adopted to comply with the now-voided advisory opinion.

The BOE last fall adopted a policy to differentiate between school-sponsored and private trips. School-sponsored trips include academic and athletic competitions, band festivals and robotics tournaments, and trips related to curriculum that are open to an entire class or grade level. The state procurement code applies in choosing tour companies for school-sponsored trips, and teachers can still travel free as chaperones on such trips but cannot be involved in negotiating with travel companies.

Meanwhile, private travel would have to be arranged separately from the school by people acting in their private capacity without the use of state resources or facilities.

Stephen Schatz, deputy superintendent for the DOE, called the judge’s decision a step in the right direction.

“We’ve been arguing for some time that when teachers are traveling with students, they are doing so for the educational experience of their students, not for personal benefits or gifts,” Schatz said in a statement, adding that the department will consult with its attorneys on future action.