Trey Anastasio was accused of driving under the influence of drugs in an upstate New York town near the Vermont border early Friday.
The former Phish frontman was pulled over by an officer who saw his car failing to keep to right side of the road at about 3:30 a.m., Whitehall village police said.
A search turned up quantities of the painkillers hydrocodone and Percocet, as well as the anti-anxiety drug Xanax, that had been prescribed for someone else, police said.
Anastasio, who was driving with a suspended New York license, was charged with third-degree aggravated unlicensed operation, seventh-degree criminal possession of a controlled substance and driving while intoxicated-drugs, police said.
The 42-year-old guitarist was released and scheduled for a court appearance at a later date.
Anastasio lives in Vermont and has been performing solo since Phish broke up in 2004.
The Phish tour was well-known for its active drug scene, and Anastasio said in a 2005 Associated Press interview that part of the reason he went solo was to escape that atmosphere.
Asked how sobriety had affected him, he said, "It affects you positively in every possible way that you can imagine, 'cause it's YOU. ... Any feeling you're trying to achieve using hard drugs you're gonna achieve through sobriety."