I'm asking this question in the context of the Jian Ghomeshi sexual assault trial here in Canada. Many critics of yesterday's decision are outraged that he was not forced to testify during the trial, while the complainants were subjected to withering cross-examination. I know that this is a long standing principle in British common law (the Fifth Amendment of the US Constitution stipulates that no person "shall be compelled in any criminal case to be a witness against himself"), but where does it come from? Does it have its roots in the Magna Carta or does it have a more recent origin? Were there particular trials in which this principle was established?
This is the privilege against self incrimination. "The Historical Origins of the Privilege Against Self- Incrimination at Common Law" John H. Langbein, Yale Law School Faculty Scholarship Series (PDF) has a thesis that prior historical scholarship was incorrect to locate the origins of this privilege in the second half of the seventeenth century in connection with the abolition of the courts of Star Chamber, etc. The author (paraphrasing) asserts that from the mid sixteenth century until late in the eighteenth century, the fundamental safeguard for the defendant in common law criminal procedure was not the right to remain silent, but rather the opportunity to speak. The defendant apparently was denied the right to a lawyer. This was gradually relaxed, leading to the modern right to refuse to answer questions.
Not a direct answer, but it's worth keeping in mind that, traditionally, defendants were prohibited from testifying at all under English Common Law. Originally, all interested parties were barred from speaking, but the bar on defendants testifying would last, in some jurisdictions, until the end of the 19th Century (the first statute in the United States allowing a criminal defendant to testify was Maine in 1859).
The reason for the right to remain silent goes hand-in-hand with the presumption of innocence (basically, it's the government's job to prove guilt, it's not the job of a defendant to prove innocence and requiring him to speak will inevitably make the trial center around his credibility). I just want to make the context clear that, when the right developed, testimony by defendants was generally prohibited (and, in fact, this prohibition continued by many who supported the right to remain silent because they felt to allow otherwise would undermine the right).