Can an individual be charged with selling an illegal substance if they are not in possession? I was wondering if a person could be charged with selling something like drugs, illegal firearms, or stolen items if they are never caught possessing them? I have seen in movies where they will take payment and then say that the location will be given to the buyer later via a call or text. Is this enough evidence to charge the seller with crime? I have heard phrases like possession is 9/10 of the law. Then you hear of kingpins like El Chapo getting arrested and it makes you wonder. Seems like most kingpins never touch the merchandise at least on TV. Is it the same in real law? Could a dark web seller be charged selling drugs if they are never caught possessing them? You hear of dark web drug sales a lot on the net. Is this why it's so common?
As an example, read Ross Ulbricht - Wikipedia. He was convicted of "money laundering, computer hacking, conspiracy to traffic fraudulent identity documents, and conspiracy to traffic narcotics by means of the Internet," not the actual possession of drugs. He thought he was smart enough to escape culpability if he didn't directly handle the actual merchandise sold on the Silk Road (marketplace) - Wikipedia, but there was overwhelming evidence that he conspired to sell the merchandise, the merchandise was illegal, that he had proxies to accept money and launder it and proxies to ship the merchandise, and that's what convinced the jury.
It is their property, so keeping it without permission could well be seen as theft. I think you are obliged to make reasonable attempts to notify them you have their property before using it or selling it. Just like if someone left the item at your house after a party. If they want it back, however, it is at their cost, you should not be out of pocket for their failure to deliver within a reasonable time-frame; you may find they've already claimed the cost of the product from the courier and don't want it back. You are well within your rights to offer to buy it from them, and them to accept or reject that offer, this is a separate contract to the original sale.
A person's property cannot be seized in the US except by due process of law. There is no law that declares the property of a convicted person to be forfeit to the state. A person who is convicted might be subject to a fine, in which case a court could order seizure of property to pay the fine. Your property might also be seized as a result of a civil forfeiture proceeding (where the government sues your property for being the fruit of an illegal enterprise), but that only applies to property believed to be connected to a crime (e.g. purchased with the proceeds of a crime). Civil forfeiture doesn't even require that you be arrested. Barring that circumstance, the person retains their rights to their property. It is then up to them to make suitable arrangements for the protection or disposition of their property.
In the US, police do not put a person under house arrest, instead, the courts do, as an alternative to standard imprisonment (either awaiting trial, or serving their sentence). The police are not involved at all; the courts cannot be sued for lenient sentencing. If a person leaves their house (even to buy a bottle of milk), they will have violated the terms of their more lenient sentence, and will be arrested and sent to regular jail. Generally, police are not liable for damages, especially when they fail to be omnipotent in their efforts to prevent others from doing wrong.
There is, as far as I can see, no Crown exemption from the sale of goods acts (including the International Sale of Goods Conventions), but unfortunately for this patient the NHS has no liability either in logic or in law. The doctor provided a written prescription, for which there is no charge, and which allows patients to buy certain drugs. The patient took the prescription to a chemist's, which (for money) provided the drug specified in it. Even if the patient had noticed that the prescription was for the wrong form of medicine, the pharmacist has no discretion to alter it; if the prescription specifies tablets, the patient can either buy the tablets or not buy them and take the prescription back to the doctor. In neither case has either the doctor or the chemist committed any conceivable offence regarding sale of goods. (There might theoretically be a case for negligence, but it would never be worth either suing a doctor for an £8 prescription fee or reporting him to the authorities for writing a prescription for the right drug in the wrong form).
(assuming United States law here, though I'd be surprised if it were significantly different in other jurisdictions with such restrictions) Your friend is incorrect: that would be a new offense, for which Person A could be prosecuted anew. If your friend's logic were correct, once a person is convicted of robbing a store, they'd be free to rob that store without repercussions for life. It's worth noting that the conviction isn't relevant: the prohibition of double jeopardy in the United States prevents even multiple prosecutions (except, in some cases, for separate state and federal prosecutions or foreign prosecutions).
A contract that tells one party or another to do an illegal thing is void ab initio: courts will not recognize it or give force to it. A contract which doesnt explicitly tell either party to do something illegal but if during the course of fulfilling either party's end of the bargain they commit an illegal act it is up to the courts discretion what happens, whether to find the contract void or to maintain the contract (its a matter of public policy whether they allow the contract to continue existing, or if the contract was such that illegal acts were expected to be commited then the court will likely remder it void) Either way, you cannot indemnify someone for committing an illegal act.
How come this is viable? Because it’s legal. What if people use their service to commit crimes? What if people use a Ford in a bank holdup? Or a Glock in a murder? Or the US Postal Service in a Nigerian letter scam? If the goods or services are legal and not provided for an obviously illegal purpose, nothing happens.