SPRINGFIELD — Following the lead of the 7th U.S. Circuit Court of Appeals, the state’s high court overruled a 1978 precedent used to determine Sixth Amendment violations.In a 13-page opinion issued today, the Illinois Supreme Court ruled unanimously that the precedent in People v. Echols is at odds with the U.S. Supreme Court’s 1980 decision in Cuyler v. Sullivan.The defendants in both Echols and Sullivan argued they received ineffective assistance of counsel because their attorneys faced a conflict of …