Only the ACLU would think of this: They have banded with parents and student of Palm Beach County and mounted a trailblazing class-action lawsuit, the only of its kind (ever?), claiming that students' constitutional rights are being violated by the incredibly horribly awful schools there, which result in low graduation rates, particularly among blacks and Latinos.The county, for its part, says it'd doing a fine job, of course. So let's look real quick at the numbers.According to the ACLU's "most generous" interpretation of the statistics, one third of students don't graduate. According to a more realistic calculation, they say, it's closer to half. This could get interesting...