OSAKA — The Osaka District Court on Monday ruled against a 1993 move by Sanwa Bank to punish its employees who had contributed to a book accusing the major commercial bank of discriminatory labor practices.

Presiding judge Tetsuo Matsumoto said the 19 plaintiffs, who have sued the Osaka-based “city” bank seeking to invalidate the punishment, had sufficient reason to believe that they had been unfairly treated by the bank, blaming the bank for “abuse of its authority to punish its workers.”

While ruling that the punishment was invalid, the judge turned down the workers’ demand that the bank pay them 1 million yen each in compensation.

The plaintiffs comprised 17 current and two former employees of the bank, one of whom has died.

They contributed articles to a book, published in 1992 by an Osaka publishing company, charging that the bank discriminated against some of its employees in terms of promotion and job transfers based on gender and political inclinations.

They also complained that the bank forced them to work overtime without paying extra wages.

Sanwa management reprimanded the 19 employees, saying they had damaged public trust in the bank with their “slanderous” statements.

The workers then sued Sanwa, saying that its punishment against them violated their freedom of speech. They argued that their articles are based on facts and that the bank management was not justified in penalizing them for the book.

After examining each plaintiff’s case, Judge Matsumoto said the bank’s punishment was invalid, concluding, “The bank failed to provide convincing reason why the plaintiffs’ wages are kept low, and the plaintiffs have sufficient reason to believe that they had been discriminated against.”

“The (plaintiffs) wrote the articles to have the bank improve their working conditions, and workers have the right to criticize (their employer’s) management policy,” the judge said.

Lawyers for the plaintiffs said they are “100 percent” satisfied with the ruling, hailing it as a landmark decision that clearly recognizes workers’ freedom to publish to correct unfair treatment by their employers.

A Sanwa Bank spokesman said the court’s decision was regrettable, adding that it will closely examine the ruling.