In the case of Gilbert v. California, 1966, the U.S. Supreme Court ruled that handwriting exemplars taken from a defendant are not protected by the Fifth Amendment's protection against self-incrimination because they do not constitute compelled testimonial evidence. The court also held that taking such samples does not violate Fourth Amendment rights against unreasonable searches and seizures if done with proper legal process or consent. However, in this particular case, it was determined that an in-court identification of Gilbert had been tainted by a police station lineup conducted without counsel present after his indictment (thus violating his Sixth Amendment right to counsel). Despite this violation, the conviction was upheld due to overwhelming independent evidence proving guilt beyond reasonable doubt.

In the dissenting opinion for Gilbert v. California, Justice Harlan argued that handwriting exemplars taken from a defendant without their consent do not violate the Fifth Amendment's protection against self-incrimination. He reasoned that such samples are physical evidence, not testimonial or communicative in nature and thus fall outside of Fifth Amendment protections. Furthermore, he contended that even if these exemplars could be considered as incriminating themselves, they were still non-testimonial and therefore permissible to obtain without violating constitutional rights. Justice Harlan also disagreed with the majority's decision to exclude all derivative evidence obtained through an illegal lineup identification process; instead suggesting each case should be evaluated individually on its own merits regarding whether due process was violated.