The son of Rep. James P. Moran on Wednesday pleaded guilty to assaulting his girlfriend, admitting to a role in an alcohol-fueled incident outside a Northwest Washington nightspot this month.

Patrick B. Moran, 23, of Arlington County pleaded guilty to one count of simple assault, a misdemeanor.

A D.C. Superior Court judge suspended a 90-day jail term and sentenced him to one year’s probation.

Moran will also have to complete domestic-violence counseling and 50 hours of community service.

According to a police account of the Dec. 1 incident contained in court documents, an officer saw Moran grab a woman by the back of her head and slam it into a trash can about 1:23 a.m. in front of the Getaway nightclub in Columbia Heights.

Moran and the woman were separated, court documents say, and police later learned that she had been his girlfriend for six months.

The two had argued inside the club after Moran spoke with another woman, according to court documents.

A e-mailed statement from Kelly Hofmann, Moran’s girlfriend, that was circulated by his father’s office after the plea had been entered called the incident one that “has been blown out of proportion” and said she was hurt when one of her high heels gave out and she fell into a trash can.

Another statement released by a spokesman for the congressman (D-Va.) also called the incident an “accident.”

Moran’s court-appointed attorney, Gretchen Franklin, said that the couple was still together and that prosecutors declined to dismiss the case even though Hofmann wanted them to.

By all accounts, alcohol played a factor in the incident. Franklin said Moran and Hofmann had been drinking; the statement from James Moran’s office also said the incident “involved drinking.”

Patrick Moran was initially charged with felony assault. Hofmann was found bleeding “heavily” from her nose, according to court records, and her nose and right eye were “extremely” swollen.

Moran resigned from his post as field director for his father’s reelection campaign in October after a conservative activist released an undercover video of Moran discussing potential ways to commit voter fraud.

Arlington police and Virginia Attorney General Ken Cuccinelli II said they would investigate the incident, in which Moran was captured in the video suggesting that someone could use forged utility bills as proof of voter eligibility.

Patrick Moran said at the time that he had not taken the undercover campaign worker seriously and was merely trying to “humor him.”

But he also acknowledged that he should have “immediately walked away” from the person and said he was quitting the campaign so he would not “be a distraction.”

An Arlington police spokesman said Wednesday that the investigation into that incident was “ongoing.”

Allison Klein and Clarence Williams contributed to this report.