In preparation for the lay judge system, which recently started, public prosecutors and police began partially videotaping the interrogation of suspects on a trial basis in August 2006 and in September 2008. The videotaped scenes are of investigators reading the record of a suspect's oral statement to the suspect, who then signs it. The videotaping serves as evidence.

But the experience of Mr. Toshikazu Sugaya, who was released in June on the strength of a new DNA test indicating his innocence — after he had served 17 years of a life sentence for the 1990 murder of a 4-year-old girl in Ashikaga, Tochigi Prefecture — appears to reinforce the case for videotaping all of the interrogation process.

Mr. Sugaya said he got scared during his interrogation after police officers shouted in his face, pulled his hair and kicked him. The interrogation lasted 13 hours. Confronted with the result of an original DNA test in the crime, he confessed to it.

Although they officially apologized to Mr. Sugaya, police and public prosecutors remain reluctant to videotape the whole interrogation process. The reason for this opposition, investigators say, is that they must first build a relationship of trust with a suspect by asking about his family situation and background, and by showing understanding and sympathy toward him or her, before delving into the crime in question.

Investigators say that if a suspect knows that his or her privacy will be made public in court through videotaping, he or she will not open his heart to investigators, thus hampering the investigation. They also worry about acts of revenge being taken against a suspect who is considered a "gangster" once other gangsters learn that the suspect's disclosure of information on accomplices or the ring leader in a crime has been videotaped and fear being implicated themselves.

Obviously, some arrangements may become necessary to protect privacy and prevent acts of retaliation. But Mr. Sugaya's case clearly undermines the reason for opposing complete videotaping. The scope of the discussion on the matter could widen to touch on such issues as the introduction of a plea bargaining and wider use of a sting operation.