What's the equivalent phrase in the UK for "I plead the fifth"?

In the United States, a person under examination on the witness stand may "plead the fifth" to avoid self-incrimination. In other words, a person asserts his or her Fifth Amendment right.

Citizens of many English-speaking countries have the right to remain silent and laws to protect against self-incrimination (testifying against yourself). In the UK, how do witnesses or defendants respond in court? Do they literally remain silent, invoke a particular law, or say "no comment"?

Include the legal traditions of other English-speaking countries if relevant. However, with nearly one hundred such nations, I don't wish to promote giving an answer for each one.

To be clear: I am looking for the words a defendant might say on the witness stand. If there's no standard response, then that's an acceptable answer. If defendants would never say something like it because they wouldn't be on the stand unless they had waived their right to silence, then that's an acceptable answer.

Solution 1:

There is no such equivalent phrase that I know of for any English-speaking country. However thanks to the prevalence of US media, the phrase "plead the fifth" or "take the fifth" is widely recognized outside the US, and is frequently used in general conversation

In most jurisdictions that derive from the British system, a defendant may decline to testify in court. However once they have agreed to testify they cannot then decline to answer some questions. Likewise, in Canada at least, testimony given as a witness in someone else's trial cannot be used against you. This means that there is no case where a witness can decline to answer a specific question, and so there is no equivalent phrase that is used in court.

Edit: Kudos to @AndrewLeach for pointing out the well-known "right to remain silent" in police interrogations, which also exists in the UK and most places with a British-derived system of justice. I believe in general conversation "I'm exercising my right to remain silent" would be understood in much the same way as "I plead the fifth".

Solution 2:

In a UK court, there is no right to silence and no equivalent of the Fifth Amendment. Witnesses swear or affirm to tell the truth, the whole truth and nothing but the truth. Telling the whole truth means that nothing can be left out. If a question is inconvenient, tough. Naturally, giving that undertaking doesn't stop perjury. It's not necessary for a defendant to testify in his own defence (and thus have to answer potentially awkward questions), because the prosecution has to prove their own case. But if he does testify, he makes the same oath/affirmation and has to answer everything.

However, there is a right to remain silent and not answer questions during a police investigation. "You have the right to remain silent..." — but it continues "it may harm your defence if you do not mention when questioned anything you later rely on in court." Courts have the right to discount evidence adduced which was not forthcoming during questioning.

[This answer relates to England & Wales and Northern Ireland. Scottish law is different and this may not apply there. Needless to say, but it's necessary so I'll say it anyway, ELU is not a law site and nothing here constitutes legal advice.]

Solution 3:

Although it is sometimes more circumscribed than the Fifth Amendment -- particularly after passage of several laws in the late 20th century -- there is a common-law "right to silence" or "right to remain silent" in the UK (or England and Wales at least).

The "right to remain silent" is the more common modern usage, perhaps affected by the reading of Miranda rights on rebroadcast American television. Compare a Google search of *.uk sites for "right to silence" (~2000 hits) vs "right to remain silent" (~4000 hits).

Solution 4:

There is no set phrase, but before an advocate takes a witness into areas where self-incrimination is possible, he is required to explain the relevant law (which is essentially that nobody can be required to prove the prosecution's case against himself). Usually this explanation will include some such phrase as 'you may in those circumstances decline to answer', so the witness says simply 'I decline to answer'.

(source: personal experience in the civil courts)