Hoi Eng Chan does not know how all those unbundled un-broken-down cardboard boxes wound up in front of the house she owns in the Bronx. It is near the subway, so a lot of people throw trash there.

Aminur Howlader concedes that the rice in the steam table of the Halal food cart he operates was being held at less than 140 degrees, but he was going to throw it out. He had already made a whole other cooker of rice and was serving from that instead. As for the other summons, Mr. Howlader’s cart was indeed parked less than 20 feet from a door of the Target on Avenue H, but that door is used only by employees when the store is closed, which it wasn’t. He has been parking in that spot for nine years and never got a ticket.

This is life at OATH, a little-known but ever-expanding branch of the municipal justice system. OATH, the Office of Administrative Trials and Hearings, now handles violation summonses from 19 city agencies, from the health department to the Fire Department to the Business Integrity Commission. OATH hears about 100 times more cases than all the criminal courts in the city put together.

A day spent in the hearing rooms of an OATH office — there is one in each borough — offers both a voyage into the small intestine of bureaucracy and a front-row seat at an endless and sometimes heartbreaking parade of excuses and ostensibly exculpatory explanations.

Sometimes injustice is exposed and defeated. Sometimes it is as if a pack of homework-eating dogs is roaming the streets.

The folding table from which Liudmyla Sviderska was selling pastries without a permit on Brighton Beach Avenue was not a mobile food cart, her representative said. Also, they were just pastries from a nearby bakery that got an A on its health inspection. Also, the pastries were individually wrapped and not potentially hazardous. Everyone else on 23rd Road also lets their tenants park illegally on the side of the house. Hector Sanabria would have pleaded not guilty to the open-container summons but he does not remember what happened that day.

If courthouses, with their columns and marble and carved mottos, are built to inspire awe at the majesty of the law, the aesthetics of an OATH hearing center, with its box-office windows and crowd-herding cordons, will be immediately familiar to anyone who has done time at the D.M.V.

The judges do not wear robes or carry gavels. They are per-diem city lawyers in business attire and are known as hearing officers.

Defendants — they are called respondents — may bring a lawyer, but most do not. The agency that issued the summons can send a representative, and some routinely do. But the Sanitation Department, which accounts for nearly half of the summonses processed by OATH, nearly never sends anyone. Nor does the Police Department, another leading summons source. So most of the time, it is just the respondent and the hearing officer in the little room.

It is not Arjan Gjushi’s fault if the subcontractors brought their dumptrucks to the site more than an hour early and blocked Featherbed Lane. It is not Metin Kurtulus’s fault if patrons of the bodega next to his vacant lot throw their empty bottles over his fence, especially after he chained his own trash can to a post for them to use and someone stole it. Strokos Gourmet Deli has fired the exterminator responsible for the 46 live fruit flies a health inspector observed on a recent visit.

Over the course of many hearings, patterns of excuse emerge. Very frequently, they hinge on evasion or transfer of blame. This is a risky legal strategy.