In the case of J.D.B. v. North Carolina, the U.S. Supreme Court ruled in 2011 that age is a relevant factor to consider in determining whether a suspect should be read their Miranda rights during police interrogations under custodial circumstances. The petitioner was a 13-year-old student who had been questioned by law enforcement at his school regarding recent burglaries without being given Miranda warnings or an opportunity for parental presence during questioning. He later confessed and was charged with breaking and entering as well as larceny; however, he argued that his confession should not be admissible because he was not informed of his right to remain silent or have an attorney present before interrogation began - essentially arguing that he was "in custody" when questioned at school even though no formal arrest took place there. The court agreed (5-4), stating minors may feel more coerced than adults due to their lack of experience and understanding about legal matters, hence they might not feel free to leave such situations despite officers' claims otherwise – thus making them effectively "in custody". This landmark decision established new precedent on how juveniles are treated within the criminal justice system.

In the dissenting opinion for J. D. B., Petitioner v. North Carolina, Justice Samuel Alito argued that considering age as a factor in determining whether an individual is in custody for Miranda purposes would complicate law enforcement practices and undermine the clarity of Miranda warnings. He contended that introducing age into the analysis could lead to consideration of other personal characteristics such as intelligence, education, and experience with law enforcement – all subjective factors difficult to assess at the time of arrest or questioning. Furthermore, he expressed concern about how police officers would be expected to accurately determine a suspect's age during an encounter without infringing on their rights or making assumptions based on appearance alone.