Why are involuntary confessions not admissible in Anglo-American law?

In Anglo-American law, involuntary confessions are inadmissible as evidence primarily due to concerns regarding their reliability and the fundamental principles of fairness in criminal justice.12

Historically, the legal system recognized that confessions obtained through duress, such as physical force, threats of violence, or oppressive interrogation, are inherently untrustworthy. Because such methods are likely to render a confession unreliable, they are barred to protect the integrity of the judicial process.13

Furthermore, the exclusion of involuntary confessions upholds the ethical principle that forcing individuals to incriminate themselves violates fundamental human rights. In the United States, this protection is enshrined in the Fifth Amendment of the Constitution, which guards against compelled self-incrimination. Consequently, courts require that confessions be made voluntarily, placing the burden on the prosecutor to demonstrate that a statement was not the product of coercion or oppression.413