The Grand Bench of the Supreme Court is seen in this March 15, 2017 file photo. (Mainichi)

Sexual intent is not a prerequisite for establishing the crime of indecent assault, the Grand Bench of the Supreme Court ruled on Nov. 29, altering a judicial precedent dating back to 1970.

In making the decision, supported unanimously by the 15 justices on the bench, the top court dismissed an appeal by a 40-year-old Yamanashi Prefecture man who had been sentenced to 3 1/2 years' imprisonment, finalizing his sentence.

The ruling alters a 1970 Supreme Court decision which stated that sexual intention was necessary to establish a crime of indecent assault. Referring to a June 2017 revision to the Penal Code which included tougher penalties for sex offences, the Grand Bench said it reflected changing perceptions in society toward sex crimes and the victims of those crimes.

"Today, in interpreting what constitutes a crime, we should rather focus on whether the victim has suffered any sexual damage and the details and extent of such damage, and so the 1970 judicial precedent is difficult to maintain," the court said.

The 40-year-old man had been charged with touching and taking nude photographs of a girl aged under 13 in 2015. In his trial, he denied that he acted with sexual intent, saying that he had been asked to photograph the girl following a request for money.

Lower court rulings had deemed the man guilty, saying it was not appropriate to apply the 1970 decision. Lawyers for the man appealed to the top court on the grounds that the lower court decisions violated a legal precedent.

Cases are deliberated by the 15-member Grand Bench of the Supreme Court when they involve decisions relating to the Constitution or on alteration of judicial precedents. The latest case marks the first time in 14 years for the court to alter such a precedent, following a case involving interpretation of the crime of embezzlement in 2003.