A judge violated the Sixth Amendment when he prevented a defendant accused of robbery from representing himself at a pretrial hearing, a federal appeals court has ruled. The 7th U.S. Circuit Court of Appeals on Tuesday conceded that self-representation generally ends badly — particularly for people facing criminal charges. “No doubt the old adage ‘a lawyer who represents himself has a fool for a client’ applies in spades if for ‘lawyer’ we substitute ‘criminal defendant …