Residents recounted how police will conduct a “sona,” slang for mass interrogation in communities that often leads to harassment by the authorities. I was told in one slum by the Pasig River that more than 80 men were called out of their homes, lined up and arrested last September. One woman said that a few of those detained ended up dead. Another woman, whose brother was similarly killed, spoke on behalf of her sheepish husband standing behind her. A model citizen in the community, he serves as a volunteer firefighter, heads the local group that organizes an annual religious procession and had just before his arrest passed a police clearance that was required for new employment. To raise his $500 bail, his family sold their shanty, gave up their small business and moved in with his mother.

Such stories are now commonplace. The poor, who’ve always known justice least, now bear injustice most. While Mr. Duterte remains overwhelmingly popular, a recent poll showed that trust in him has risen among the upper classes but has dropped by 11 percentage points among the poorest, resulting in a seven-point drop overall.

In a slum in the north of Manila, residents told me about a dozen men from the same street who were arrested this year after a police raid failed to snag a targeted drug suspect. Women showed me documents issued by the courts or Public Attorney’s Office, bearing labyrinthine legal phrases in English, a language they barely speak. To these citizens, the rotten justice system is the only place to which they can turn.

Human rights lawyers say such systemic injustice can be addressed only by reforming the judiciary, the penal system and the police together. But that network must first be challenged, to prove that its dysfunction results in grave consequences, and the only ones who can legally file cases are the abused parties, most of whom are too poor and too scared to do so.

That is steadily changing. Whistleblowers from among police and vigilantes are speaking out, while lawyers’ groups have been working on cases for victims of abuse or families of those killed. This year, a group of claimants won an injunction from the Supreme Court, which issued a restraining order against police officers alleged to have shot four men execution style. Yet the trial is a long way off, and these plaintiffs, and all others like them, receive no other protection from the government. They live in fear.

If not for concerned lawyers who advocate for them, the journalists who tell their stories and religious groups who offer sanctuary, these citizens, who mostly do not know their rights, would be facing the system entirely on their own. There’s an inspiring irony that the strength and courage most needed to challenge it all comes from the country’s most vulnerable.

These cases, often dismissed by Duterte supporters as isolated incidents or necessary growing pains, are actually vital to the reform this administration seeks. Without them, a public advocate told me, we can neither prove that abuse indeed stems from the system nor pinpoint what needs to be fixed. And given the current government’s efforts to reinstate capital punishment and lower the age of criminal liability to 9 years old, fixing the Philippine justice system is more than ever a matter of life and death.

Despite his violent rhetoric and his coddling of police, the blame is not all Mr. Duterte’s. No one person is culpable, just as no one person can fix it. What is supposed to be a precision instrument for ensuring law and order has become a weapon so blunt that most people can’t trust it. The current embrace of violence, and all the justifications people make for it, are predicated on this. The system is so broken that many Filipinos think it’s just better to purge the dregs of society. It’s a perverse hope — one that if we’re honest we can all understand, but one that if we’re responsible, we must ultimately reject.