In the case of Coy v. Iowa in 1987, the U.S. Supreme Court ruled that a defendant's Sixth Amendment right to confront witnesses against them was violated when a screen was used to shield two minor victims from seeing the defendant during their testimony in a sexual assault trial. The court held that face-to-face confrontation is not absolute and may be limited if necessary for public policy reasons such as protecting child witnesses from trauma, but there must be specific findings showing this necessity on a case-by-case basis. In this instance, no such finding had been made; therefore, using the screen without demonstrating its necessity infringed upon Coy's rights under the Confrontation Clause of the Sixth Amendment.

In the dissenting opinion for Coy v. Iowa, Justice O'Connor argued that the majority's decision was too rigid and failed to consider individual circumstances of each case. She contended that a blanket rule prohibiting all use of protective screens in child abuse cases could potentially harm victims who might be traumatized by facing their abusers in court. Instead, she suggested a more flexible approach where trial judges would have discretion to decide on a case-by-case basis whether such measures were necessary to protect the mental health of child witnesses while also ensuring defendants' right to confrontation. Furthermore, she disagreed with the majority's interpretation of "face-to-face" confrontation as an absolute constitutional requirement under Sixth Amendment rights; rather, it should be balanced against other important interests like protecting vulnerable witnesses from further trauma.