If a court witness self-implicates are they automatically charged? If a witness under oath in court gives evidence that reveals they have committed a previously unknown crime or offence, are they automatically charged or is there another process that may or may not be followed before they are charged? They don't have an explicit immunity agreement, they have just revealed evidence that implicates them. The crime or offence doesn't have to be the one before the court. An example from TV: A man is asked how he was in a position to witness the assault. He says, "I was in my garden at the time ritually slaughtering a goat." He comes from a country where ritually slaughtering goats is done by civilised people and he genuinely doesn't realise that it's illegal in this country. Nobody could anticipate that he would say that in advance and warn him not to. Would he be automatically charged or would it be discretionary? I am particularly interested in Australian courts.
In the US, they would not be automatically prosecuted. The prosecutor would have to find out about the testimony, decide to prosecute, and go through all the normal processes they otherwise would, but they have an additional piece of evidence. Per the 5th Amendment to the US Constitution, a witness cannot be forced to answer a question that would incriminate them. If the question was objected to on this ground and the objection overruled, the witness' answer would not be admissible against that witness at trial, and the prosecutor would have to prove the case using other evidence.
There’s some truth in it When a matter, particularly a criminal matter, is before a court or sub judice, public comment is forbidden and may be contempt of court unless they are “a fair and accurate report of legal proceedings held in public, published contemporaneously and in good faith.” Technically, it only applies to media reporting (probably including social media) and only while the proceedings are active. Proceedings become active when there is an arrest, oral charge, issue of a warrant, or a summons. Notwithstanding, there is nothing preventing an organisation having a “no comment” policy on any matter once there is police involvement.
There is a big difference between knowing something and proving it. A lawyer who knows a client is guilty can take steps to prevent the state from proving guilt. (E.g., motion to exclude evidence, cross examining witnesses.) The belief that a client has committed a crime does not necessarily mean one knows what specific crime was committed. Is a killing Murder 1, Murder 2, or manslaughter? There are defenses even when an act may be a crime. E.g., self defense, insanity, justifiable. Lawyers are not permitted to assist in perjury. E.g., allow the client to testify to something he knows is false.
In every U.S. jurisdiction this is controlled by Rule of Professional Conduct 3.7 which is modeled on the American Bar Association's Model Rules of Professional Conduct, although the exact language is not perfectly uniform. It says: Advocate (a) A lawyer shall not act as advocate at a trial in which the lawyer is likely to be a necessary witness unless: (1) the testimony relates to an uncontested issue; (2) the testimony relates to the nature and value of legal services rendered in the case; or (3) disqualification of the lawyer would work substantial hardship on the client. (b) A lawyer may act as advocate in a trial in which another lawyer in the lawyer's firm is likely to be called as a witness unless precluded from doing so by Rule 1.7 or Rule 1.9. In a criminal prosecution, exceptions (a)(2) and (a)(3) almost never apply. A prosecutor's fees are generally paid by the government without reimbursement from criminal defendants making (2) inapplicable, and there are almost always multiple prosecutors in the same prosecutor's office making (3) unlikely as well. In rare instances where every prosecutor could be disqualified as a witness (e.g. a crime taking place physically within an all office meeting of the prosecutors office where no one was absent), a prosecutor from another jurisdiction in the same state would be appointed as a special prosecutor to handle the case due to the de facto conflict of interest. Rules 1.7 and 1.9 are conflict of interest rules, which rarely apply unless a crime is directed at the prosecutor's office itself, or perhaps was allegedly committed by a prosecutor (in which case a special prosecutor is appointed to address the conflict). Otherwise, another lawyer in the same office can handle the case that the lawyer who was a witness cannot. So, in practice, in criminal cases, prosecutor testimony only concerns uncontested issues pursuant to (a)(1) (e.g. testimony that venue is proper because the city of Evergreen is located in Jefferson County, Colorado, or that the defendant was arrested on the date shown in the police report). Note also, that the lawyer-witness rule applies only to advocacy at trial. A lawyer who is trial witness can still participate, for example, in motion practice, in directing colleagues in trial preparation, in interviewing witnesses prior to trial, in making plea bargaining decisions, in scheduling conferences, and in appellate work in the case. Official comment number 2 explains the justification for the rule: The tribunal has proper objection when the trier of fact may be confused or misled by a lawyer serving as both advocate and witness. The opposing party has proper objection where the combination of roles may prejudice that party's rights in the litigation. A witness is required to testify on the basis of personal knowledge, while an advocate is expected to explain and comment on evidence given by others. It may not be clear whether a statement by an advocate-witness should be taken as proof or as an analysis of the proof.
The answer provided by Dale M is half right, but there are a few things that I think are wrong. Firstly, the actual reality of the situation doesn't matter. What matters is that you act in a reasonable manner, performing assessments of the situation as a reasonable person would do. If you misread the situation, and end up killing a police officer that was acting in a lawful manner, it doesn't necessarily mean you were acting unlawfully yourself. Because police officers are generally exposed to situations where they would be forced to use their firearm, that obviously would impact how a reasonable person would see the situation, but the test for reasonableness would not go out the window. In addition, even if you were found to not be acting in a reasonable manner, there is certainly a question if you would be found guilty of a lesser charge of manslaughter rather than murder. It's possible the self-defence claim would be upheld as an imperfect defence.
Not all illegal things are crimes. Lack of evidence. They are asked to testify, and they say "what I said in my book was a lie". There is no general law against lying, except when under oath. Statute of limitations. Saying "10 years ago I did smoke drugs" means that any offence is no longer prosecutable. Lack of details. Which jurisdiction were they in? When did they commit the act, how many acts? You cannot be arrested for being a "bank robber" or a "murderer". You are charged with "robbing Bank X on 123 Fake Street the Thursday 25 April 2018" or "murdering Jim Thio in January 2017". Otherwise the defendant would have a hard time defending himself (how to prove that you have not killed anyone at any time?) All of the above combined with prosecutorial discretion in the form that any possible prosecutor will most likely determine that bringing charges would be just a waste of time and resources. UPDATE February 2018: Just for the sake of completeness, a reference to the situation of Jacques Cassandri, who did boast about a serious crime(a robbery in a Societe Generale vault in 1976) in a book. Unfortunately for him, he made some kind of mistake/miscalculation and the crime had not yet expired, so he has become an example of someone being prosecuted by confessing a crime in a book.
“Anything you say can be used against you in court.” Is what the police say in the USA. “You are not obliged to say or do anything unless you wish to do so, but whatever you say or do may be used in evidence. Do you understand?” is what they say in New South Wales. “You do not have to say anything, but it may harm your defence if you do not mention, when questioned, something which you later rely on in court. Anything you do say may be given in evidence.” is what they say in England and Wales. And so on. Whether Mark wants to mention that he was robbing a bank on the far side of town at the time is entirely up to him. If he does, and that can be verified it’s likely the murder charges will be dropped and armed robbery charges will be brought instead. Note that in many jurisdictions, if the defence intends to use an alibi defence, the prosecution must be told about it at a very early stage or it can’t be used at all.
The answer to this question will be almost entirely informed by the why that you've asked us not to consider. If the prosecutor or judge is a witness, the defendant should be able to call them, but that also means they would have to withdraw from the case under either Rule 3.7 or Canon 3. If the defendant believes the prosecution is tainted by some improper motive, the defendant may raise that objection under Crim. R. 12, but he must do so pretrial. I can't think of any circumstances where the defendant could question the judge or prosecutor in the jury's presence.