Da Brat Juror -- Sentenced To Do Homework -- After Screwing Up Trial

The juror who caused a mistrial in Da Brat's assault case by lying about his citizenship -- just got the legal equivalent of high school detention ... because the judge ordered him TO WRITE AN ESSAY as punishment.

We broke the story ... Dante Leon Chavarria was held in contempt after the judge found out he had lied about being a U.S. citizen when he was called for jury duty.

Chavarria spent two days in the slammer for causing the mistrial. But even worse than that ... the judge ordered him to write an essay on the origins and importance of the U.S. Jury system ... and read it aloud in open court.

Chavarria's lawyer tells TMZ ... Chavarria didn't mean to lie ... he's a Mexican citizen who's here in the U.S. legally on a visa ... and had simply been confused by the judge's questions.

We're told Chavarria was nervous reading his essay aloud since English isn't his first language ... but the judge seemed satisfied and we're told there won't be any more criminal charges.