In Japan’s criminal justice system, which is said to have a 99.9% conviction rate, 12 people have already been definitively acquitted in four cases related to the crackdown on Kan-nama.

On March 6, 2023, Presiding Judge Makoto Wada of the Osaka High Court cited Article 28 of the Constitution and ruled that the activities of Kan-nama as a labor union were legitimate.

“As an industrial union, Kan-nama is protected by the guarantees of the right to organize and other rights under Article 28 of the Constitution; therefore, any legitimate actions taken to defend these rights are exempt from illegality.”

However, on June 9, 2025, the same Osaka High Court handed down a ruling that disregarded Article 28 of the Constitution. It found members and former members of Kan-nama guilty of attempted extortion and obstruction of business by intimidation against a construction company. They were sentenced to two years and six months in prison (suspended for three years) and one year and six months in prison (suspended for three years), respectively.

The presiding judge was Yuko Tsuboi. She expressed the view that union activities within a company are only allowed if members of Kan-nama are employed there. It is a misconception that Article 28 of the Constitution exclusively applies to in-house union activity.

In 2023, the UN Working Group on Business and Human Rights visited Kan-nama. Following its fact-finding mission, the Working Group expressed concern over the criminal persecution of Kan-nama and issued the following report.

“The essential role of labour unions in promoting fair and lawful workplace practices. The Working Group reiterates the importance of labour unions being able to carry out their activities in a legitimate manner.”

Judge Tsuboi’s ruling is at odds with both the Constitution and international norms.

Compliance activities and “Heinrich’s Law”

The charges stemmed from “compliance activities” carried out against a construction company at a construction site in Shiga Prefecture.

Compliance activities refer to the process in which union members visit construction sites to ensure that regulations and procedures are being properly followed. For example, they check to see if materials are protruding into walkways, if there are any vehicles with expired inspections, or if tire treads are worn down, and report any deficiencies they find.

At first glance, it may seem like a mundane task, but it is one of the union activities that Kan-nama values highly.

Yoichi Take, vice chairman of Kan-nama, was involved in the investigation of collapsed expressways and buildings during the 1995 Great Hanshin-Awaji Earthquake. He found that the interior of columns, which were supposed to be made of reinforced concrete, was hollow and filled with trash such as five-gallon cans, rubber boots, debris, and safety shoes. To cut costs, trash had been used in place of concrete. This shoddy construction led to many casualties.

Take recounts, “If labor unions don’t strictly enforce compliance, things are going to go haywire.”

Satoshi Yamamoto, an executive committee member of Kan-nama, is also keenly aware of the importance of compliance activities on a daily basis.

“What worries me most is causing troubles to civilians. That’s the worst thing that could happen. At large construction sites, dump trucks and other vehicles come and go, and fatal accidents happen from time to time—like when a pedestrian gets run over. Construction sites account for the highest number of workplace accidents. Hearing about these incidents makes me realize we really need to step up our compliance activity.”

It is common knowledge in the field of occupational safety that even minor mistakes can lead to major accidents if they accumulate. To prevent workplace accidents, Herbert William Heinrich of the United States proposed “Heinrich’s Law.”

According to this rule, for every major incident, there are 29 minor accidents and 300 near misses.

Pointing out safety hazards at construction sites is essential not only for the safety of civilians but also for the safety of workers. It is a fundamental responsibility of labor unions.

However, on June 9, 2025, Presiding Judge Yuko Tsuboi of the Osaka High Court ruled that compliance activities constituted a means of obstructing business operations or extorting companies. She stated that gravel and fencing protruding from the construction site onto the road constituted “minor deficiencies” and were “trivial matters.”

Different rulings at the Osaka High Court

The following points in Judge Tsuboi’s reasoning are fundamentally flawed.

“Since it does not target the employers of Kan-nama union members, it does not constitute labor dispute action.”

The argument is that if no union members are employed by the company in question—whether in compliance-related activities or labor disputes—such activities do not constitute labor union activities.

However, this reveals a complete lack of understanding of the labor union activities guaranteed by the Constitution. Labor unions are not limited to the in-house unions that are mainstream in Japan; unions organized by industry, such as Kan-nama are also recognized by the Constitution. There is consensus on this point even among labor law scholars. In December 2019, 78 labor law scholars issued a statement protesting the criminal crackdown on Kan-nama.

It is clear from a ruling issued by the same Osaka High Court just two years ago that Judge Tsuboi is wrong.

In March 2023, during a trial in Wakayama in which Kan-nama was charged with union activities, Presiding Judge Makoto Wada of the Osaka High Court cited Article 28 of the Constitution and recognized the legitimacy of the union members’ activities.

“Since Kan-nama, as an industrial union, can be regarded as a party to labor relations alongside the management and employers of companies in the industry or their respective organizations, it is entitled to the protections guaranteed by Article 28 of the Constitution, including the right to organize, and any legitimate actions taken to safeguard these rights are exempt from illegality.”

All three were acquitted. The prosecution decided not to appeal, and the acquittals are now final.

UN Working Group on Business and Human Rights investigates crackdown on Kan-nama

Judge Tsuboi is also ignoring international norms.

From July to August 2023, a team from the UN Working Group on Business and Human Rights visited Japan. They investigated the crackdown on Kan-nama by law enforcement agencies and included the following in its report.

“(Kan-nama) Members faced legal action under charges of the alleged forcible obstruction of business and attempted extortion, stemming from their participation in daily union activities focused on advocating for corporate compliance with laws and regulations.”

“The Working Group notes the essential role of labour unions in promoting fair and lawful workplace practices, which help to ensure that business enterprises respect human rights, as outlined by the Guiding Principles. Therefore, the Working Group reiterates the importance of labour unions being able to carry out their activities in a legitimate manner.”

“Is this the kind of person who judges others?”

What kind of legal professional is Judge Tsuboi?

She graduated from Kyoto University. She has primarily handled criminal cases. She has served as a judge at the Otsu District Court, the Kyoto District Court, and the Osaka District Court. At the Osaka District Court, she served as a presiding judge.

While serving as presiding judge at the Otsu District Court, she once rejected a petition for retrial in a case that was later found to be a miscarriage of justice.

This refers to the “Koto Memorial Hospital Incident,” which occurred in Shiga Prefecture in 2003. A nursing assistant was sentenced to 12 years in prison for causing the death of a patient by pulling out the patient’s ventilator tube. After the nurses’ release, a retrial began, and she was acquitted in 2020.

However, the request for a retrial was initially denied. In September 2010, a petition for a retrial was filed with the Otsu District Court, but the request was dismissed. Tsuboi presided over that hearing on the petition for a retrial.

Following the Osaka High Court’s ruling, the defendant, a member of Kan-nama, spoke with Tansa.

“I kept looking at the judge, but our eyes never met. I thought to myself, ‘Is this what a judge is like? Is this the kind of person who judges others?’”

The defendant’s defense team filed an appeal with the Supreme Court the very same day.

(Originally published in Japanese on June 9 2025. Translation by Mana Shibata.)

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