In the case Gonzales v. United States (1954), the U.S. Supreme Court ruled that a defendant in a federal criminal trial has the right to have their sanity evaluated by an independent psychiatrist before standing trial, even if they are unable to afford one themselves. The court held that it was not sufficient for only government-appointed psychiatrists to evaluate the defendant's mental state as this could potentially lead to bias and infringe upon their rights of due process under law. This decision emphasized on ensuring fair trials and protecting defendants' constitutional rights, particularly those who may be mentally ill or impaired.

In the dissenting opinion for Gonzales v. United States, Justice Jackson disagreed with the majority's decision to uphold a lower court ruling that denied Gonzales' request to have counsel present during his grand jury testimony. He argued that this violated his Sixth Amendment right to legal representation. Jackson contended that the Constitution does not distinguish between different stages of criminal proceedings when it comes to providing defendants with their rights and protections, including access to counsel. He also expressed concern about potential abuse by prosecutors who might take advantage of unrepresented witnesses in grand jury proceedings, leading them into self-incrimination or perjury traps without proper legal advice and protection.