As set forth in Kennedy v. Cardwell, the problems in shackling a defendant include:
1) Shackles may impair the defendant's mental faculties; 2) physical restraints may impede communication between the defendant and his lawyer; 3) shackles may detract from the dignity and decorum of the judicial proceedings; 4) physical restraints may be painful to the defendant.
The danger inherent in imposing physical restraints is the possibility that the defendant may feel confused, frustrated, or embarrassed, thus impairing his mental faculties. Zygaldo v. Wainright.
The U.S. Supreme Court in Illinois v. Allen stated that binding a defendant should be considered a last resort.