A Hennepin County judge ruled there wasn't probable cause to determine a crime was committed by Culpepper, one of four Minnesota Vikings accused of misdemeanor lewd conduct during the cruiseon a suburban lake. Culpepper has since been traded to the Miami Dolphins.
Judge Kevin Burke denied a motion to dismiss charges against running back Moe Williams.
The other two players charged, cornerback Fred Smoot and tackle Bryant McKinnie, weren't part of Tuesday's ruling. Their next hearings are scheduled for Thursday.
Culpepper didn't immediately respond to an e-mail seeking comment.
His attorney, Earl Gray, said, "I'm happy about it. I'm sure Culpepper is, and his family. It vindicates him from being involved in any sexual misconduct on the boat."
Williams' attorney, Joe Friedberg, said he was disappointed.
"I disagree with him, but that's what makes horse racing," Friedberg said.
Both Culpepper and Williams had denied any improper conduct in a hearing before Burke last month. Culpepper, who was accused of touching a dancer's buttocks, testified that he spent the cruise on Lake Minnetonka playing a dice game in the back of a boat and rejected offers from several women.
Williams, accused of touching a dancer's breast, testified that a woman danced near him but he never touched her.
In explaining his ruling, Burke wrote Culpepper's version of events would clear him if true, and since the prosecutor offered nothing to rebut it, he found no probable cause. The difference with Williams, the judge wrote, was that his story wouldn't necessarily exonerate him.
Both players also claimed that race played a factor in prosecutor Steve Tallen's decision to charge them. They pointed out that two white men, including the captain of one of the boats, weren't charged even though investigators found evidence the men both kissed a stripper's exposed nipple.
Burke said the claim was understandable, but the prosecutor had discretion on who was charged.
Tallen denied at last month's hearing that race was a factor, saying the case against the white men was shaky. He was in court Tuesday and didn't immediately return a phone message.
The boat party scandal was the lowest point in a dismal season for the Vikings, who lost Culpepper to a serious knee injury soon afterward. After his relationship with the team and new head coach Brad Childress soured in the off-season, he was traded to Miami last month for a second-round pick.
All four players faced identical charges of indecent conduct, disorderly conduct and lewd or lascivious conduct. Conviction on a single misdemeanor charge is punishable by up to 90 days in jail and/or a $1,000 fine.
Williams' trial is scheduled for April 18.