The ongoing trial of Satoshi Uematsu, accused of killing 19 people and injuring many others at a care home for people with mental disabilities in Sagamihara, Kanagawa Prefecture, in July 2016, should provide an opportunity for all of us to reflect on whether he is alone in judging the value of other people's lives based on how useful or productive they are to society.

Until just a quarter century ago, this country had a law that authorized the forced sterilization of people with mental disabilities in order to prevent the birth of "eugenically inferior" offspring, and it was only last year that a compensation program was legislated for the victims and they were offered a government apology. Discrimination against people with disabilities remains deeply rooted in our society. Instead of only highlighting the accused's distorted — and despicable — views toward his victims, we should think hard about whether society at large shares any of his ideas behind the grisly murders.

Since surrendering himself to police after the fatal knife rampage against the care home residents four years ago, Uematsu, a former employee of the facility, has insisted that he killed the victims to do good for society as people with heavy disabilities are useless and only bring misfortune, and thus should be euthanized. He has reiterated similar arguments in the trial that opened last month. He claims he is mentally competent to stand trial, rebuffing the plea of innocence on grounds of insanity made by his own lawyers.