He was found guilty of assault and spent the next six months in solitary confinement.

Assault on prison workers may seem like a straightforward infraction, but a closer look reveals a disturbing pattern. There were 1,028 such violations issued in the state system last year. Black men received 61 percent of them, while white men received 9 percent. Under department rules, officers have considerable leeway over what constitutes an assault. An inmate need not cause an injury or even touch an officer.

About 20,000 uniformed officers work in the state’s prisons. During the first half of the year, 2,007 of them were involved in assault cases, according to department data, but 98 percent of them had no injuries or only minor ones, which can be as vague as “aches/pain.” Eight officers suffered serious injuries, defined as a broken bone or a puncture wound.

The Times reviewed 215 reports of assaults on staff from the first quarter of 2015, obtained through a Freedom of Information Law request. The department redacted the officers’ names but not the inmates’. It also redacted most information about injuries, but in several cases, The Times was able to obtain medical records through the prisoners.

Among those reports, the cases of three black inmates — Darius Horton, Paul Sellers and Justin Shaw — followed the same pattern: All were involved in seemingly trivial disagreements with guards that led to minor altercations. And while it is hard to know who was responsible for escalating the episodes, the officers were not injured and remained on duty, while the inmates were punished with long stints in isolation.

Mr. Sellers was returning from dinner at Five Points Correctional Facility when he was stopped by an officer for taking “a loaf of state bread” back to his cell, according to the guard’s report. “Surrender the bread,” the officer ordered. Mr. Sellers refused and grabbed the shirt of the officer, who punched him in the face. He was sent to solitary for 166 days.

Mr. Shaw was stopped at Washington Correctional Facility because he was “attempting to conceal contraband,” according to the officer’s report. When challenged, “the inmate produced a stack of waffles,” the report said. Mr. Shaw was accused of then grabbing the officer’s arm and given a 180-day lockup.

Mr. Horton was caught by Officer Michael Stamp at Groveland carrying a bowl of hot water from the microwave for coffee after the common room had closed. The officer ordered Mr. Horton to leave it, he refused and they got into a shouting match and bumped shoulders, according to the report. The guard claimed that Mr. Horton then punched him. In an interview, Mr. Horton denied this, saying he was jumped by Officer Stamp and six other guards. Two of the officers had minor injuries; the other five were unharmed. Mr. Horton was sentenced to 270 days in isolation.