A volunteer firefighter was socked in the face while trying to stop the occupants of two crashed cars from fighting.

And Royce Mercer, the 17-year-old who allegedly threw the punch in a December 2018 Waihi Beach melee, now faces an assault charge.

According to court documents, he told police he was very drunk and didn't remember hitting the firefighter.

Mercer had never appeared in court before this charge, but came up before Judge Thomas Ingram in Waihi District Court in early January.

The punch happened in the context of a "violent and disorderly" confrontation between people in two vehicles involved in a crash, according to the summary of facts.

Mercer was a passenger in one of the vehicles which crashed on December 1, 2018, on Snell Crescent in Waihi Beach.

The fighting didn't stop when volunteer firefighters from Waihi Beach arrived, so they tried to keep the scrapping groups apart until police could get there.

Mercer attempted to push past one of the firefighters and was prevented from doing so, the summary says.

"He has then punched the [firefighter] once to the face, causing his nose to bleed.

"In explanation, the defendant stated that he was very drunk and did not remember assaulting the fire fighter."

Mercer had applied for diversion but it was declined, the duty lawyer who saw him said.

He also entered an intimated guilty plea.

Judge Ingram agreed to remand Mercer until January 21, so he could get legal aid.