In September, police took a 17-year-old African-American boy out of high school in Cincinnati, Ohio, and arrested him on the suspicion that he had participated in an armed mugging. There was no evidence connecting him to the alleged crime, his public defender contended, save that the alleged victim brought the boy's Facebook photo to the police. The charges were dismissed, but only after the boy spent a month in detention, including time in isolation, according to a lawsuit filed last month.

The class-action lawsuit, filed on behalf of juvenile plaintiffs against two officials at Hamilton County juvenile court system, claims that the boy's case is part of a systematic problem in Hamilton County -- and possibly throughout Ohio -- where officials authorize warrants for arrest and incarceration without probable cause determination, which has a disproportionate impact on black children. The lawsuit also is filed against the Hamilton County Board of County Commissioners.

Pamela Matthews, 46, the legal guardian of the boy, "S.W.", said that when she heard her son had been taken out of history class and put in jail, "I assumed it was a joke; I started laughing." Her son is a good student with no juvenile criminal record, according to his sworn court testimony, and Matthews said that he had a solid alibi: "He was at home, asleep."

According to the Cincinnati Police Department incident report filed on Sept. 7, the victim claimed that he was robbed by three teenagers, one of whom was described as having "dreads with blonde tips," and the other two of whom are only listed as being male and black and wearing certain clothing.

Ali Hatheway, a senior trial attorney at the Hamilton County Public Defender's office who handled S.W.'s criminal case and is not involved with the lawsuit, told The Huffington Post that "he didn't even fit the physical description."

"There was nothing, other than what this kid was saying," Hatheway said, calling the case "one of the worst ones I've handled with there being a lack of probable cause." She added, "Here it does happen a lot, where you can just go down to the juvenile detention center and say, 'Hey, so-and-so threatened to kill me' ... and now there's a warrant."

According to Matthews, the only evidence provided to her by law enforcement was a photo of S.W. standing in Matthews' mother's laundry-room, making a gun gesture with his fingers, which the alleged victim's family found on Facebook.

The detective who worked on the case and the police officer who filed the initial report did not respond to multiple requests for comment.

According to the lawsuit, in 2013, African-American children in the county were almost 10 times more likely to be arrested than white children, and two times more likely to be placed in secure detention. The complaint alleges that the court did not make a probable cause determination for S.W. during the 30 days he spent in detention, not attending his high school.

"I was very scared because I thought no one would believe I was innocent," S.W. testified.

On Oct. 10, a judge dismissed S.W.'s case "on the merits," according to court documents. Hatheway said the alleged victim's story fell apart. "I think it was a situation where he came in late at two in the morning and he didn't want to get in trouble, so he made up this story about getting robbed, and it just snowballed," Hatheway said.

Curtis Kissinger, the court administrator for the Hamilton County Juvenile Court, said that juveniles typically get a hearing within 24 hours with a defense attorney present, where police statements are reviewed. "There's no testimony being taken at that first hearing," he said. After that, there are additional weekly reviews of youth in detention, although he noted, "We don't go into an assessment of the truthfulness of the allegations; we don't delve into potential guilt" at those reviews.

Kissinger said that while he couldn't comment on S.W.'s case in particular, he pointed out that the court is "following state law and the rules promulgated by the Ohio Supreme Court." He added, "The plaintiffs have an issue with those rules."

Indeed, the lawsuit notes that, "Ohio law does not explicitly require a probable cause finding at a detention hearing," although the detention must be "constitutionally valid." Jill Beeler-Andrews, chief counsel of the Ohio Public Defender Office's Juvenile Division, told the Gongwer News Service that judges not taking probable cause under consideration during detainment hearings "is happening pretty regularly throughout the state."

Last year, over 6,000 children were arrested in Hamilton County, about 40 percent of them detained in the Hamilton County Juvenile Court Youth Center. The daily cost of holding each child is $221, according to the Children's Law Center, which filed the case.