In the 1971 case Adams v. Illinois, the U.S Supreme Court upheld a decision by an Illinois court that denied a defendant's request for counsel during a preliminary hearing. The defendant, Adams, was charged with armed robbery and requested legal representation at his preliminary hearing but was refused on grounds that it wasn't necessary at this stage of proceedings. He appealed to the Supreme Court arguing violation of his Sixth Amendment right to counsel under the United States Constitution. However, in its ruling, the Supreme Court held that while defendants have a constitutional right to be represented by an attorney during trial stages where substantial rights may be affected or lost; such protection does not extend to all pretrial procedures including preliminary hearings unless they are deemed critical stages where potential prejudice could result from lack of counsel.

In the dissenting opinion for Adams v. Illinois, Justice Harlan argued that the majority's decision to extend Miranda rights to preliminary hearings was unnecessary and potentially harmful. He contended that such a ruling could lead to an over-complication of pretrial proceedings, making them more formal and adversarial than they were intended to be. Furthermore, he expressed concern about extending constitutional safeguards beyond their original scope without clear justification or necessity. In his view, this expansion risked undermining the balance between individual rights and societal interests in effective law enforcement by placing undue burdens on police officers and prosecutors while not significantly enhancing protections for defendants.