What does a lawyer do if they know for absolute certain that their client is guilty? Say that a person is accused of committing a crime, they either hire a lawyer or have one appointed to them. Some time later, the lawyer learns that their client most certainly committed the crime. Perhaps the client shows the lawyer a video of them committing the crime (and it is proven to be genuine). What does a lawyer do in this case? Are they required to continue to defend their client (and would that mean they may be forced to commit perjury?) or are they allowed to choose not to continue to represent their client in the interest of finding the truth and upholding justice? If there are any historical cases where this sort of thing happened, mentioning them would be a plus. For the sake of argument, let's assume that the lawyer is somehow able to know with 100% certainty that their client committed the crime, so there is no issue of the lawyer passing judgement when there is a chance of doubt.
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.
They are not given independence from statute. This clause just says that conviction is not the end goal of the prosecutor. If in light of the evidence, the prosecutor comes to believe a person is not guilty, they are not to proceed with the prosecution. They must not hide exculpatory or mitigating evidence in order to get a conviction.
To know a defendant is guilty is to know that the government has convinced a judge or jury beyond a reasonable doubt that the defendant committed all the elements of a crime. A lawyer can't know that the government will accomplish this prior to a trial. Options for a lawyer who determines that the government has a strong case include: seeking to have evidence excluded looking for other grounds for appeals establishing affirmative defenses negotiating a plea deal for a lighter sentence or less serious crime the lawyer will continue to force the government to prove their case
In a deposition, attorneys are supposed to keep their objections short and refrain from making an objection that indicates to the witness how he should answer. A question might be objectionable because it lacks foundation, because it is compound, because it calls for speculation, etc. Example 2, for instance, could be said to assume that Ms. Redacted was involved, and I might not want my client to discuss how he would act in that situation. Some attorneys in that situation might say, "Objection, assumes that Ms. Redacted had anything to do with this, which you haven't proved, and it's impossible to say what would have happened under circumstances that never happened." This gives my client a pretty clear signal that he ought to make clear that Ms. Redacted wasn't around, and that he should try to avoid getting pinned down on any questions about what he would have done if she had been. This practice -- known as "a speaking objection" -- can be used to signal to the witness how best to answer, and it leads to huge fights in a deposition. To avoid those fights, courts have developed a practice of requiring lawyers to simply "object to the form," rather than coaching the witness. That puts the objection on the record so it isn't waived, and if it's truly problematic, the parties have an opportunity to explain in greater detail after the deposition is concluded.
This is one of the things Martha Stewart was convicted of. 18 USC 1001 is the US federal law requiring truthfulness. That statute forbids you to falsify, conceal, or cover up a material fact. One limitation on how broad this law is, is that it has to be a matter "within the jurisdiction of the executive, legislative, or judicial branch of the Government of the United States". If your neighbor is an FBI agent and he asks if you're the one who broke his window, and you lie, that's not a federal matter. Another limitation is that the lying has to be material. The essential part of the law is subsection (a). Subsection (b) then states an exception: (b) Subsection (a) does not apply to a party to a judicial proceeding, or that party’s counsel, for statements, representations, writings or documents submitted by such party or counsel to a judge or magistrate in that proceeding. Then you also owe a lesser duty of truthfulness to the legislature. Taking note of US. v. Yermian, it is not required that the person you lie to be a federal officer. Yermian lied to his employer, who was a defense contractor, and the fact that the relevant form was submitted to the government for scrutiny is what made it a matter in federal jurisdiction. Comparing the wording of 1001 to the perjury statute, the operative expression for perjury involves statements "which he does not believe to be true", we can see that the perjury statute requires telling the literal truth (see Bronston v. US), which allows so-called lies of omission (of a particular subtype: much more could be said about that). In contrast the lying statute forbids both literally false statements and concealing of the truth. I don't have cases at my fingertips that indicate how broad your truthful answers have to be, for example if you think the FBI is trying to put away a friend and ask you about what he did on June 14, and you know that he did a bad thing on June 13, would it be lying in the relevant sense to conceal that fact which they didn't ask about. [ADDENDUM] A session of perusing cases has led to a tiny bit of further information. A literal reading of the statute says that you are in violation of the law if you falsify a fact (sloppy epistemology, unless it refers just to altering records and evidence), or conceal a fact, and the courts recognise this as a fundamental division. As for falsifying, the way that has been applied is to refer to cases where the accused makes a statement which asserts something that he knows to be untrue. Thus, saying "No" to a question when the truth is "Yes" is a violation. A propos concealment, in US v. Diogo 320 F.2d 898 the court states that False representations, like common law perjury, require proof of actual falsity; concealment requires proof of wilful nondisclosure by means of a 'trick, scheme or device.' This case is pre-Bronston so there is mixing of concepts from perjury law and lying law, which would not happen now, but we can steering clear of their perjury citations. The crucial fact is that accused(s) were technically married in New York, for immigration purposes, and they were accused of a 1001 violation for having indicated that they were married. Part of the government's case was that such a marriage is not valid, and the court rejected that conclusion. The government's second prong was to maintain that the court "should affirm appellant's convictions on a theory of concealment", and this too the court rejected, saying "proof of their ulterior motives in marriage would not be tantamount to proof of willful and knowing concealment of these material facts". What they said on the forms was literally true, and they did not have a duty to volunteer information that they probably knew the government was interested in. Contrarily in a later case, US v. Zalman 870 F.2d 1047 we are told that the underlying purpose of a marriage is a material fact which bears upon the validity of the marriage, and that any false or fraudulent misrepresentation regarding the actual purpose of a marriage in order to gain status as a resident of the United States can be punished under 18 U.S.C.A. § 1001 so you have to be more truthful than the literal truth standard. There are also circumstances where there is an independent duty to give information, such as reporting income to the IRS. In US v. Hernando Ospina 798 F.2d 1570 the court maintained It is clear that in order to support a section 1001 concealment conviction there must be a legal duty to disclose the facts the defendant was convicted of concealing citing US v. Tobon-Builes 706 F.2d 1092, where again there was a legal duty to report "existence, origin, and transfer of approximately $185,200 in cash". In other words, it is not clear what information you are allowed to not volunteer when asked a question in a federal matter.
No. As the defendant's lawyer, they will have been privy to privileged communications. As such, it would be unfair to the defendant if they now started prosecuting. Also note that a victim very rarely has their own lawyer in a criminal case. The prosecution lawyer is acting for "the Crown" (essentially, "society as a whole"). (There are exceptions, if the victim is bringing a private prosecution - but this is very rare for serious cases such as rape).
The misunderstanding The only person who can chose to prosecute or not to prosecute a criminal case is the state: in the US this is through the office of the relevant District Attorney advised by the police. When a person makes a complaint to police (or other authorities), the police/DA commence an investigation. In an ideal world all complaints would be investigated rigorously and thoroughly, however, we live in this world. The police/DA will assess the complaint and decide if it warrants the dedication of scarce resources to investigate. One of the factors they will consider is how vigorously the complainant prods them in the ass. Ultimately, the police/DA will decide if there is enough evidence to place the matter before the courts. The complainant has no say in when or if this will happen. A complainant cannot "drop the charges"! The misconduct For a police officer to disclose to another police officer that they were the subject of a felony (or any) complaint is gross misconduct and a huge betrayal of trust. At best it shows poor judgement, at worst it is corrupt. Your friend needs professional legal advice right now!
The best course would be to contact the public defenders office and explain the situation to their intake or consultation services. Remember, you don't have to be going to trial to avail yourself of their services and sometimes, helping cops makes the cops suspicious about you (it would not be the first killer who cozies up to the police to learn what they know about his crime). If the Public Defender thinks you're rich enough not to need their services, you should call criminal defense attorney practices. Most law offices will offer consultation free of charge as part of client intake, so they will be willing to hear your case and offer advice. In either case, check with the lawyer that attorney client privilege is in effect. If they say yes, explain in detail to them, everything you know and want to discuss, even if some of it could criminally implicate you in this or another crime. Treat it as your deathbed confession and you know full well which circle of hell you're going to if the priest doesn't absolve you of sins (okay, too Catholic... but the Lawyer is not going to turn you in if the privilege is in effect... he could lose his license to practice law over it... we can make all the evil lawyer jokes we want, but this is one of the few sacred tenants of their profession.). Listen to his advise. Also see if you can find a second opinion. It's not that the first guy gave bad advice, but the next guy might give you something different. If you still do not feel comfortable, then keep your mouth shut. If they arrest you for the murder, do not talk until you have an attorney present and prepare to tell him exactly what you did. Especially if you did do it. Always answer your attorney truthfully.