In People v. Zehr, 103 Ill. 2d 472, 469 N.E.2d 1062, 83 Ill. Dec. 128 (1984), the Illinois supreme court held that a trial court erred during voir dire by refusing the defense counsel's request to ask potential jurors about their understanding and acceptance of the State's burden of proof, about defendant's right not to testify, and about the presumption of innocence. Zehr, 103 Ill. 2d at 476-78. The supreme court held that "essential to the qualification of jurors in a criminal case is that they know: (1) that a defendant is presumed innocent; (2) that he is not required to offer any evidence in his own behalf; (3) that he must be proved guilty beyond a reasonable doubt; (4) that his failure to testify in his own behalf cannot be held against him." Zehr, 103 Ill. 2d at 477. These four principles are now commonly referred to as "the Zehr principles." In Zehr, the Court held that "essential to the qualification of jurors in a criminal case is that they know that the defendant is presumed innocent, that he is not required to offer any evidence on his own behalf, that he must be proved guilty beyond a reasonable doubt, and that his failure to testify on his own behalf cannot be held against him." Zehr, 103 Ill. 2d at 477. If a juror has a bias against any of these basic guarantees, an instruction given at the end of the trial will have little effect. Zehr, 103 Ill. 2d at 477. In Zehr, the supreme Court of Illinois held a trial court erred during voir dire by refusing defense counsel's request to ask questions about: (1) the State's burden of proof; (2) the defendant's right to not testify; (3) the presumption of innocence. Zehr, 103 Ill. 2d at 477-78, 469 N.E.2d at 1064. The supreme court amended Rule 431(b) to assure compliance with its decision in Zehr. Adopted March 21, 2007, and effective May 1, 2007, the rule now reads as follows: "The court shall ask each potential juror, individually or in a group, whether that juror understands and accepts the following principles: (1) that the defendant is presumed innocent of the charge(s) against him or her; (2) that before a defendant can be convicted the State must prove the defendant guilty beyond a reasonable doubt; (3) that the defendant is not required to offer any evidence on his or her own behalf; (4) that the defendant's failure to testify cannot be held against him or her; however, no inquiry of a prospective juror shall be made into the defendant's failure to testify when the defendant objects. The court's method of inquiry shall provide each juror an opportunity to respond to specific questions concerning the principles set out in this section." Official Reports Advance Sheet No. 8 (April 11, 2007), R. 431(b), eff. May 1, 2007.