Technical innovations in DNA forensic science modeled on practices in the United States, as well as introduction of the lay judge system, are creating a framework that could provide lawyers and those who may have been wrongly convicted with access to various experts to help bolster their cases.

But many hurdles remain on the road to change.

Keiko Aoki and Tatsuhiro Boku, who had been serving life sentences for lighting a fire that killed Aoki’s 11-year-old daughter, were freed late last month after 20 years behind bars.

The Osaka High Court concluded that a retrial was appropriate as the fire could have been accidental, citing the results of an experiment conducted by the couple’s lawyers to simulate the actual blaze.

Moreover, doubt was cast on confession by Boku, Aoki’s de facto husband, as the simulation demonstrated the fire could have been accidental.

In 1990, Toshikazu Sugaya was arrested and later sentenced to life by a Tochigi Prefecture high court for the murder of a 4-year-old girl. Key in the murder conviction was DNA evidence found on the victim’s clothing that prosecutors said matched Sugaya’s.

But with the primitive forensic technology at the time, more than eight out of every 1,000 people would have also drawn an identical DNA match.

After spending 17½ years in prison, a further DNA test in 2009 conclusively showed that Sugaya was innocent, and he was acquitted and awarded about ¥80 million in government compensation.

Perhaps even more sensational due to the international attention it garnered was the case of Govinda Prasad Mainali, a Nepalese man who was wrongly jailed for 15 years while serving a life sentence for the 1997 murder of a female Tokyo Electric Power Co. worker who reportedly had moonlighted as a prostitute.

The Tokyo High Court ordered a retrial after sets of exculpatory DNA evidence were linked to an unidentified man who had sexual contact with the victim just hours before her death. Mainali was released and deported back to his native Nepal after he was exonerated in November 2012.

Swabs of semen recovered from the woman’s body that the prosecution deemed too small of a sample to analyze using the existing technologies at the time were tested in 2011 and determined not to be from Mainali.

Mainali was later awarded ¥68 million in compensation for his wrongful imprisonment.

Former professional boxer Iwao Hakamada, who had been sentenced to death over the 1966 murder of four members of a family, was released after nearly 48 years behind bars when test results indicated that the DNA type from bloodstains detected on five items of clothing believed to have been worn by the culprit differed from Hakamada’s.

The blood was thought to be that of the attacker and determined unlikely to be from any of the victims.

Although Hakamada initially admitted to the charges, he changed his plea to innocent when the trial opened.

Prosecutors in Japan have a staggering 99 percent conviction rate. Confessions are in most cases considered the strongest evidence and acquittals are anathema to ambitious prosecutors and judges alike, experts argue.

Although it may appear that retrials are on the rise, many observers point out that without “convincing and fresh” evidence the courts remain reluctant to order retrials. And even with fresh evidence — unless it can conclusively prove a person’s innocence — requests for retrials have historically been denied.

Inspired by the U.S.-based Innocence Project, researchers in Japan aim to launch a support network next spring for people believed to have been wrongly convicted.

Mitsuyuki Inaba, a professor at the College of Policy Science and Graduate School of Policy Science at Ritsumeikan University, is spearheading the project. He has criticized the lack of remorse expressed by investigators in wrongful conviction cases and says more must be done to determine the root causes and prevent them.

“In the world of engineering, when an airplane accident occurs, a thorough investigation is conducted,” Inaba said. “But what on earth are the people involved in laws doing when serious human error is committed in the cases of wrongful convictions?”

The Innocence Project, which was founded in 1992 at the Benjamin N. Cardozo School of Law at Yeshiva University in New York City, is a nonprofit organization.

In questionable cases, scholars, journalists and lawyers work together to gather new evidence in response to convicts who claim innocence. New technology such as DNA testing, as well as researching cases from fresh perspectives, have resulted in retrials and acquittals of some death-row inmates.

Similar activities have spread to countries such as France, Australia and Taiwan, creating a more global network.

Kana Sasakura, an associate professor of the Konan University Faculty of Law in Kobe, said Japanese courts will not allow retrials unless fresh evidence is strong enough to overturn the original judgment, but collecting such proof remains extremely difficult.

“Unlike in ordinary criminal trials, there is no system for court-appointed defense lawyers, who are publicly financed, at retrials,” said Sasakura. “It is very difficult for convicts held in prisons and detention houses to collect new evidence by themselves that could overturn their convictions.”

Sasakura remains hopeful that eventually the Japanese university project will gain nonprofit status.

“In the future, it would be desirable for the Japanese project to be operated like an NPO, raising donations from the public,” Sasakura said. “For the time being, however, it will probably be operated more stably by having the head office at a university, which will be useful for education if students are interested in joining.”