In the first ruling of its kind in Illinois, a state Appellate Court decided Wednesday that a Roman Catholic priest could not sue two brothers who say he molested them. Enabling Rev. Robert Stepek to sue the men who cooperated with a church investigation would infringe on religious liberties granted by the U.S. Constitution, a three-judge appeals court said in its decision to order the trial court to throw out Stepek’s lawsuit. Allowing the suit would require a court to examine how the church disciplines clergy — a move that would conflict with the “free exercise [of religion] clause of the 1st Amendment,” the ruling said. In 2006, Stepek was removed from the pulpit at St. Albert the Great Church in Burbank after a review by the Chicago archdiocese determined there was reasonable cause to suspect that sexual abuse of minors occurred when he was at St. Symphorosa Parish in Chicago in the early 1980s.