The US Olympic swimmer was stopped for speeding after being caught going 84mph in a 45mph zone early on Tuesday morning, police in Baltimore said. He was co-operative, but failed a series of standard sobriety tests.
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Michael Phelps has apologised following his DUI arrest on Tuesday morning
Michael, who is the most decorated Olympian ever with 22 medals, was charged and released.
The 28-year-old later apologised via Twitter for his actions..
"I understand the severity of my actions and take full responsibility," he said. "I know these words may not mean much right now but I am deeply sorry to everyone I have let down."
Michael retired after winning his 22nd Olympic medal at the London Games in 2012, but came out of retirement earlier this year.
With 22 medals, Michael Phelps is the most decorated Olympian ever
It is the sportsman's second DUI arrest; he was previously charged for driving under the influence in Maryland in 2004 at the age of 19.
"I made a mistake," he said at the time. "Getting in a car with anything to drink is wrong, dangerous and unacceptable.
"I'm 19 but was taught no matter how old you are, you should always take responsibility for your actions, which I will do."