The acquittal of former death-row inmate Iwao Hakamata earlier this year has intensified calls to overhaul Japan's retrial system.

The Legislative Council, which advises the justice minister, may start discussions as early as next spring on reviewing the system.

Hakamata, 88, was exonerated 58 years after his arrest and 43 years after he first requested a retrial following the confirmation of his death sentence.

Prolonged proceedings for retrial pleas are common in Japan. Revising the rules governing such cases is crucial to provide timely relief for those facing false charges.

"We would like to conduct a needed review of why the procedures following the retrial request took such an extended time," Prosecutor-General Naomi Unemoto said in a statement on Oct. 8. The statement was issued to announce the prosecution's decision not to appeal Shizuoka District Court's acquittal of Hakamata in the retrial.

In a standard criminal trial, prosecutors present evidence to support the charges, while defendants and their lawyers challenge the credibility of the evidence. The court then evaluates the arguments and evidence from both sides before determining the defendant's guilt or innocence.

In the case of a retrial, the court handling the request conducts hearings at its discretion to decide whether to reopen the case. There are effectively no rules governing these hearings, however.

On Oct. 9, Japan Federation of Bar Associations (JFBA) President Reiko Fuchigami issued a statement calling for urgent action, saying, "Concrete studies should be launched immediately to revise the retrial law in order to correct flaws in the law."

The term "retrial law" collectively refers to related provisions within the criminal procedure law.

One of the key issues highlighted by the JFBA and other organizations regarding deficiencies in the retrial law is the absence of clear standards and procedures for evidence disclosure.

Hakamata, the recently acquitted former death-row inmate, was arrested in 1966 in connection with the murder of a senior executive at a miso fermented soybean paste production company and three of his family members in Shizuoka Prefecture. His death sentence was finalized by the Supreme Court in 1980.

The key evidence leading to Hakamata's conviction was five bloodstained pieces of clothing, discovered in a miso tank at the company, his workplace, about 14 months after the murder.

In the second retrial request, Hakamata's defense team focused on the unusual redness of the bloodstains on the clothing, as seen in color photographs disclosed by the prosecution at the court's recommendation. The team suspected that the color appeared unnatural for clothing supposedly preserved in miso for over a year. To support their claim, the lawyers submitted a report detailing experiments in which bloodstained clothing was stored in miso, presenting this as new evidence that ultimately led to the case being reopened.

As in Hakamata's case, evidence collected by investigative authorities may sometimes contain material that could prove a convict's innocence, prompting petitioners for retrial to seek its disclosure.

No legal provisions mandate such disclosure, however, and prosecutors are often reluctant to release evidence, creating significant challenges for petitioners. In Hakamata's first retrial request, no evidence was disclosed.

Furthermore, the lack of relevant rules and regulations places proceedings entirely at the discretion of the courts, a factor widely viewed as contributing to delays in substantive proceedings.

Even if a court ultimately decides to initiate a retrial after a hearing, the proceedings can be further delayed if the prosecution files an objection. In 2014, the Shizuoka District Court ruled to reopen Hakamata's case, leading to his release after nearly half a century of detention. The prosecution's immediate appeal, however, delayed his acquittal for an additional 10 years.

The JFBA and other organizations argue that prosecutors should be prohibited from filing objections to a court's decision to reopen a case.

On Oct. 28, the prosecution said it would not challenge the decision of the Nagoya High Court's Kanazawa branch to start a retrial for Shoshi Maekawa, 59, who had served a seven-year prison term for the 1986 murder of a junior high school girl in Fukui Prefecture.

In this case, the retrial decision was finalized 37 years after Maekawa's arrest, following his second retrial request. Although the court branch had also granted his first request, the prosecution's objection led to the cancellation of that decision.

The Justice Ministry is currently discussing the retrial system at a panel on criminal procedures, which includes judges, prosecutors, defense lawyers and other experts.

The ministry is expected to decide on agenda items for Legislative Council talks on overhauling the system, drawing from discussions by the panel of legal professionals.

"It's important to continue holding a series of thorough discussions, including on whether revisions to the law are needed," then-Justice Minister Hideki Makihara said in October.