Can a person secure an entity&#39;s former employee to act as an expert witness against them? In federal court, is there any ethical or evidentiary rule that prohibits a person from using that entity's former employee as an expert witness against them? For context, I would like to use a former jail correctional psychiatrist as an expert witness to give testimony that would help establish that said jail doesn't conform to constitutional standards of mental health care.
An expert witness must be independent A former (or current) employee of a party is not independent. The court may accept their independence if the relationship was decades in the past but not otherwise. If you want the said psychologist to testify about things that happened in the jail they aren’t acting as an expert witness anyway - they are acting as a witness of fact.
Does the party have any legal leverage to engage the police (or other competent authorities apart from private investigators) to help locate the witness and serve the summons on them? Not really. Legal process is not infrequently served by a sheriff's deputy. But the deputy will not generally take any initiative to locate a person to be served beyond what it provided by the litigant. The main reasons to have a sheriff's deputy serve someone with process is the fear that the person served might react violently. Or is it just the party's bad luck that the witness cannot be located and served on? Pretty much.
No In general, there is no need for a plaintiff, defendant, or witness to attend court in person if there is a legitimate impediment to them doing so. Parties can be represented by their lawyers, testimony can be made by affidavit, cross-examination can be conducted over Zoom. During the recent pandemic, entire cases, both criminal and civil have been dealt with without anyone meeting up in person.
It would be legal for a healthcare professional to sign an NDA prohibiting them from revealing certain information to a patient. Some examples: the password to the computer system; the home phone number and address of the chief of staff. It would not be legal to use an NDA as a basis for denying a patient the right to access their medical records when the HIPAA privacy rule mandates disclosure to the patient (with exceptions).
as a witness. You secretly disapprove of the thing taking place Does this actually invalidate the document (as not properly witnessed)? No. In regard to the substance of a contract, witnessing does not imply, entail, or require approval thereof by the witness. The meaning or relevance of a witness's signature is nothing more than him or her certifying that the act of "2+ other parties entering a contract" took place indeed. And are you committing a crime by doing it? I highly doubt it, regardless the country or jurisdiction. The witness's [bizarre] act of acquiescence falls short of criminal conduct such as (1) forging someone else's signature, or (2) fraudulently "acknowledging" the presence of the contracting parties when in fact at least one of them was totally absent. Only if the witness subsequently acts in a way that hinders the purposes of the contract, thereby causing harm, the harmed party(-ies) might sue the witness for tortious interference with business or relation (or its equivalent in other non-U.S. jurisdictions). For instance, suppose a contract-based transaction requires involvement by a third party, who is hesitant to perform the transaction because suspects that the witness's signature was forged. That suspicion may prompt the third party to inquire of the witness whether he actually signed as witness to the contract. If the third party rejects the contract-related transaction due to the witness's [false] denial, the harmed party(-ies) in the contract may sue the witness for any losses (examples: bounced checks, costly delays, missing of deadlines, provable loss of business opportunities) that his false denial caused.
A private venue normally has discretion over who may attend their premises, as long as it is not because of membership in a protected class under anti-discrimination law. Note that the communication, as quoted, did not say that the banned person was a threat, but only that one of the performers felt uncomfortable. I do not think that the banned person has any legal recourse, unless they can plausibly assert that this is a case of unlawful discrimination, which the question does not suggest.
The courts do not supersede your constitutional rights, although you may believe that you have a constitutional right that isn't actually there. This article discusses the position that "due process forbids convicting an individual of a crime unless the government proves the elements of the charged offense beyond a reasonable doubt". This standard is actually not stated anywhere in the US Constitution, but it has been assumed as an implicit meaning of "due process". It sounds like you were charged with a crime, and there is most likely an applicable statute in your state that is analogous to RCW 26.50.110 in Washington. So you have the right to a trial and the prosecution would have the obligation to prove all of the elements of the crime beyond a reasonable doubt. It also appears that you did violate the applicable law and you were willing to plead guilty, as urged by your attorney. You are correct that you don't technically have to prove your innocence, but there is a practical problem that if the prosecution provides some weak evidence that you violated the law, then the jury might decide that your failure to refute the evidence means that there is no reasonable doubt. The problem is that there is a tendency for jurors to think that the defendant has to create a doubt. States differ somewhat in how they explain the burden of proof to jurors, and you might fare better in a state where the instruction is that "you must be firmly convinced". Since the attorney seems to have said that "the constitution doesn't apply to this", this is a puzzle. I would not assume (though it is possible) that the attorney was incompetent. It is possible that he was speaking of a non-criminal matter, and it is possible that you were talking at cross purposes. There is no legal situation where "the constitution doesn't apply to this", but perhaps "that constitutional limitation doesn't apply to this specific situation". Regardless of what the attorney said, your attorney doesn't violate your rights, even if he gives you bad advice. The actual court might, and then you would have a cause for an appeal. Similarly, if the district attorney reasonably believes that you are a danger to society and is prosecuting you, that is not a violation of your constitutional rights. An improper conviction would be a violation of those rights, although it might take an appeal to get the court to recognize that fact.
If a defendant has committed a crime, they would choose to self-represent to ensure that no one else would know about the circumstances of their crime. Although lawyers are ethically bound to not disclose information that would not be in the interest of their client, the decision to breach this duty would be up to the sole discretion of the individual in question. In cases where the exchanged information may used to provide evidence against the client, the lawyer is compelled to disclose the truth to the courts/law enforcement. This is deeply misguided. Criminal defense lawyers usually represent people who are guilty and there is no ethical problem with doing so, nor does this mean that the lawyer will disclose privileged information that is prejudicial to the defendant in the course of the representation. The notion that a lawyer would be compelled to testify against his client to the courts/law enforcement is simply not how the system works. It is true that a lawyer cannot ethically put you on the stand to offer testimony when the lawyer knows that your testimony to the court will be an outright flat lie, and that this lie is your strategy to prevail in your defense, but that is the sole meaningful limitation on what a lawyer can do for you. However, I can't think of a single instance, in which a desire to defend yourself at trial with a lie has caused someone to represent themselves. Usually, someone with that kind of motive will simply lie to their lawyer as well. It never makes sense to represent yourself if you are innocent and want to be acquitted of the charges against you. But, keep in mind that this is a small subset of all criminal defendants. Criminal defendants are overwhelmingly guilty of something. Usually, a criminal defense lawyer works to either exploit prosecution mistakes or lack of knowledge that prevent the prosecution from proving that guilt, or work to make sure that the defendant is not convicted of a more serious crime than the one committed, and/or work to see to it that their client does not receive an unnecessarily harsh sentence when alternatives are available. In real life, people represent usually themselves, either because they are denied access to counsel (which can be done in a criminal cases where the prosecutor waives the right to seek incarceration as a sentence), or because they are "crazy". Many people who represent themselves in a criminal cases do so because they want to proudly claim that they committed the crime as a means of obtaining of forum for public recognition of what they believe was righteous action even if this could lead to their death. Many terrorists, domestic and foreign, fall into this category. For example, the fellow committed a massacre at a Colorado abortion clinic tried to do this (if I recall correctly, he was later found incompetent to face a trial and has been committed to a mental institution until he becomes competent, if ever). Other people represent themselves out of a strongly felt guilt that they feel a moral duty to confess to, even if this means that they will face severe punishment for doing so. One subset of this group of people are people known as "death penalty volunteers" who try to get sentenced to death and try to waive all appeals and post-trial review. Sometimes they also plead guilty in the belief (often, but not always, inaccurate) that their swift guilty plea when they aren't actually guilty will protect someone else whom they know to be actually guilty. Other people represent themselves because they have deeply held, but paranoid and inaccurate views about the legal system such as members of the "Sovereign Citizens Movement" who think that if they say the "magic words" that they cannot be convicted and that lawyers are a part of a conspiracy designed to prevent them from doing so. Another situation that comes up is when an affluent person who is not entitled to a public defender as a result, chooses to represent themselves, usually with respect to a fairly minor charge like a traffic violation that carries a risk for a short term of incarceration, to save money. But, this is rarely a wise choice. But, unless you plan on pleading guilty or being found guilty at trial, self-representation does not make sense, and even if you plan on pleading guilty, a lawyer is usually worth it. For example, even if the direct consequence of a guilty plea is minor, the collateral consequences of that conviction (e.g. loss of eligibility to work in certain jobs and/or deportation and/or loss of a right to own a firearm) may be consequential and something that a non-lawyer would not realize was happening. Or, maybe you think you are guilty of crime X so there is no point in fighting the charges, but actually, the language of that statute has been defined in a manner that means you are really only guilty of less serious crime Y.