Depending on the level of coercion used, a forced confession is not valid in revealing the truth. The person being interrogated may agree to the story presented to him or even make up falsehoods himself in order to satisfy the interrogator and discontinue his suffering.
For centuries the Latin phrase "Confessio est regina probationum" (In English: Confession is the Queen of evidence) justified the use of forced confession in the European legal system. When especially during the Middle Ages acquiring a confession was the most important thing during preparations before a trial, than the method used to get the confession seemed irrelevant, de facto sanctioning the use of torture to extract forced confession.
By the late 18th century, most scholars and lawyers thought of the forced confession not only as a relic of past times and morally wrong but also ineffective as the victim of torture may confess to anything just to ease his suffering.
Developments in the 20th century, notably the Universal Declaration of Human Rights, greatly reduced the legal acceptance of forced confessions. However, for most of legal history they have been accepted in most of the world, and are still accepted in some jurisdictions.
Modern day usage
Since 2001, as part of its War on Terror the United States using the CIA operates a network of off shore prisons, called black site. Probably the most infamous of which is Guantánamo Bay detention camp. State officials have admitted to the press and in court to be using various torture techniques (authorised by the District attorney) to interrogate suspects of terrorism, sometimes after forced disappearance or extraordinary rendition by the United States.
When these systematic acts were made public by the international media the European Union, United Nations, the international press and various human rights movements condemned their practice. The US Supreme Court did not discontinue its usage and repeatedly ruled against hearing citizens that underwent forced confessions, even after they were found innocent, claiming that a trial would constitute a breach of national security.
A famous case is that of Khalid El-Masri. He appealed several times aided by different international human rights movements and lawyers, yet the US Supreme Court retained its usage of forced confession techniques, and denied a hearing of the evidence.