In a slow-moving march that filled streets, spilled onto sidewalks and stretched for miles, more than 10,000 demonstrators rallied Thursday in this small town to protest the treatment of six black teenagers arrested in the beating of a white schoolmate last year.Chanting slogans from the civil rights era and waving signs, protesters from around the nation converged in central Louisiana, where the charges have made this otherwise anonymous town of 3,000 people a high-profile arena in the debate on racial bias in the judicial system.“That’s not prosecution, that’s persecution,” the Rev. Jesse Jackson, the founder of the RainbowPUSH Coalition and an organizer of the demonstration, told a crowd in front of the LaSalle Parish Courthouse. “We will not stop marching until justice runs down like waters.”The Jena High School students, known as the Jena Six, are part of a court case that began in December, when they were accused of beating a white classmate unconscious and kicking him and a prosecutor charged them with attempted murder.The beating was preceded by racially charged incidents at the high school, including nooses hanging from an oak tree that some students felt was just for white students. The tree has been cut down.One student, Mychal Bell, 17, was convicted in June of aggravated battery and conspiracy. Those charges were voided by appeals courts, most recently last Friday. Mr. Bell has not been released from jail.Even as demonstrators marched in Jena, which is 85 per cent white, an appellate court ordered an emergency hearing to determine why Mr. Bell had not been released. Bell is the sole student who has had a trial. Amid pressure from critics, prosecutors have gradually scaled back many charges against the other five. Although the starting incident occurred about a year ago, the case has been slow to join the national conversation. After Mr. Bell’s conviction, though, the details spread quickly on the Internet, text messaging and black talk radio. Students, particularly those at historically black colleges, have also had a pivotal role in spreading the details. They poured into town after all-night bus rides. Many said they were happy to pick up the torch of the civil rights struggle. “This is the first time something like this has happened for our generation,” said Eric Depradine, 24, a senior at the University of Louisiana at Lafayette.