Phelps arrived at the courthouse in a green Mercedes with his attorney and sat with his mother and sisters in the courtroom, wearing a suit and tie. His attorney said Phelps began a treatment program immediately after his arrest, including 45 days of inpatient treatment. A letter from his doctor there was glowing, saying he was forthright and cooperative.

Phelps also is attending Alcoholics Anonymous and is continuing with therapy in Maryland.

“I now have the tools to move past this. What I did was wrong, and I made a bad mistake. I’m looking forward to having a much brighter future than I had in the past,” Phelps told the judge.

Judge Nathan Braverman told Phelps that success overcoming alcohol would not come overnight, and warned him of the consequences of another slip-up.

“You don’t need a lecture from the court,” Braverman said. “If you haven’t gotten the message by now, or forget the message, the only option is jail.”

It was not Phelps’ first brush with the law, or with drink driving. His first Drunk Under the Influence (DUI) arrest came in 2004 when he was 19. He was sentenced to probation and required to talk to high school students about alcohol awareness. Phelps pleaded guilty to the charges, but as a young first-time offender he avoided a conviction.

“I recognise the seriousness of this mistake,” he said at the time. “I’ve learned from this mistake and will continue learning from this mistake for the rest of my life.”

Another embarrassment for Phelps came in 2009, when a British tabloid newspaper published a photo of him using a marijuana pipe at a party. Afterward, Phelps was suspended from USA Swimming for three months and one of his major sponsors, Kellogg, dropped him.

Before the latest arrest, Phelps came out of retirement with his sights set on competing at a fifth Olympic Games in Rio. The plea is not expected to have any impact on those plans.

He has returned to training and a six-month suspension imposed by USA Swimming ends on March 6, allowing him to compete in the final three events on the US Grand Prix schedule. Phelps might also seek to add some international events to beef up his next year schedule, since he is also banned from swimming in next summer’s world championships in Russia.

“We’re looking at a lot of different options for competition,” his coach, Bob Bowman, said in a recent interview. “We’re just taking it one day at a time. He’s back in training, and we’re seeing how things go. We’ll look at things in March and really go from there.”

Phelps retired after the 2012 London Olympics but changed his mind a year later. Bowman said the swimmer was in much better shape, even after his DUI arrest and taking time off, than he was during his initial return to the pool.

Phelps won three golds and two silvers at one of the biggest competitions of this year, the Pan Pacific Championships in August. He was named the male athlete of the year by USA Swimming.

Phelps is the most decorated Olympian of all time with 18 golds out of 22 total medals