After an initial arraignment during which a not guilty plea was entered for him, Rep. John Lawn admitted to the facts as he faced charges of drunken driving and leaving the scene of a crash in a Boston courtroom Thursday.

After Thursday morning’s arraignment ended and he returned to the courtroom about 40 minutes later, Lawn changed the not guilty plea that had been entered on his behalf and admitted to the facts of the case. He faces a slew of fines, required alcohol treatment and education, and a 45-day loss of his license.

The OUI charge will be continued without a finding if the representative maintains a clear record for one year and the leaving the scene charge will be handled similarly contingent upon a clean record for six months.

As co-chair of the Health Care Financing Committee, the Watertown Democrat is one of the Legislature’s leading decision-makers on health care issues, which have exploded in significance in recent years due to surging costs, instability in the hospital sector, labor crunches, and the coming reductions in federal support.

Lawn was arrested at about 1:45 a.m. Wednesday on misdemeanor charges of drunken driving and leaving the scene of a crime where there was property damage, the Boston Police Department said. The arrest occurred after Lawn allegedly hit a parked car on Hancock Street, which runs alongside the State House. The police report says there was “extreme damage” to his car and “a strong odor of an alcoholic beverage emanating from” him.

Lawn made a brief statement after his second court appearance Thursday, but took no questions. He did not answer as reporters pursued him and asked whether he intends to resign from the House or if there will be a House ethics investigation into the incident.

“I’d just like to say I deeply regret my actions the other night. I take full responsibility for them. I own it, and will do everything in my power to make sure nothing like this ever happens again,” he said outside the courtroom. “I apologize to my family, my family, my constituents, my colleagues. I feel terrible and will do all I can to make sure I live a better life and a healthier life, make sure nothing like this ever happens again.”

Later, while leaving the courthouse, Lawn responded to a question about where he was Tuesday night, “I was at a private residence.” It was the only question he answered from reporters.

In addition to the 45-day loss of license and undergoing alcohol treatment education, Lawn will have to pay a $50 victim of drunk driving fund fee, $250 head injury fund fee, and an additional $250 procedural fee.

During his initial appearance before Judge Paul Tressler in Boston Municipal Court on Thursday, a not guilty plea was entered on his behalf. That is a standard practice in many District Court cases across Massachusetts. He was released on his own recognizance and was slated to have a pre-trial hearing Aug. 1.

When he returned to the courtroom to change his plea, Lawn’s attorney, Tim Flaherty said Lawn made a mistake and accepted responsibility for it.

“Mr. Lawn is 56 years old. He is a father of five children, he is widely recognized in this community,” Flaherty said. “He has made a mistake. He’s here before the court to accept responsibility for that mistake. He makes no excuse for it. He made an error coming around the corner and he didn’t have the opportunity to stop. He fully accepts responsibility. He just asks, like any other person coming before the court, to be given the mercy the court gives to first-time offenders.”

Prosecutor Assistant District Attorney Amanda Corin recommended slightly more severe penalties for Lawn: an additional 45 days without a license and an additional alcohol education program, on account of leaving the scene of the crash.

“I’m not going to treat him any differently than I would treat anyone else that comes before me,” Tressler said. “The RMV’s going to do what the RMV’s going to do. I’m going to give him the 45-day loss of license. If the RMV decides to do otherwise, they have all the authority under their administrative process to do so.”

Lawn was arrested by the Boston Police Department, with assistance from the Mass. State Police, early Wednesday morning after another driver who saw the crash followed Lawn as the representative circled the State House, and the other driver flagged down an officer.

The responding officer “observed extreme damage to the passenger side front wheel ... turned to an extreme degree not consistent with normal vehicle operations,” according to the heavily redacted arrest report. When the officer requested Lawn’s license and registration, he “detected a strong odor of an alcoholic beverage emanating from” Lawn and “further observed that the suspect’s eyes were glassy and bloodshot, and his speech was slurred.”

WCVB, which was first to report on Lawn’s arrest, said Lawn told responding officers that he was a state representative, had been coming from an event at the State House when he was arrested, and said he wanted to take an Uber home rather than take a breathalyzer test.

Lawn has represented parts of Watertown, Waltham and Newton in the House since 2011. He co-chaired a Health Care Financing Committee hearing in Gardner Auditorium earlier Tuesday. It started around 10 a.m. and lasted about four and a half hours.

As news of Lawn’s arrest spread Wednesday, House Speaker Ron Mariano, who appointed Lawn to the health care chairmanship, said he was “disappointed.”

“Driving under the influence is an incredibly dangerous and often deadly mistake, and I am relieved that no one was injured in this particular instance,” Mariano said in a statement. “Representative Lawn has just told me that he takes full responsibility for this egregious lapse in judgment, and that he will work to ensure that something like this does not happen again.”

In 2019, the Senate stripped Brockton Sen. Michael Brady of his $15,000-a-year post as Senate chairman of the Committee on Public Service as punishment for his conduct during his March 2018 drunk driving arrest, which was deemed to be a violation of the chamber’s rules.

[Colin A. Young contributed to reporting]