I murder someone in the US and flee to Canada. If Canada refuses to extradite do they then try me in Canadian courts The murder is committed on US soil. the fugitive flees to Canada. The US requests Canada arrest the fugitive, which they do. US requests extradition. Canada refuses because US has capital punishment. Does Canada now try the fugitive for murder in Canada or is the fugitive simply released?
Absent exceptional circumstances like war crimes, Canada would not try the suspect for murder. It might incarcerate the suspect, however, while engaging in negotiations with U.S. officials to try the defendant for murder in a state court or federal court with jurisdiction over the case and an agreement not to seek the death penalty.
Any duty that exists is not legally enforceable in the courts in the U.S. (there are one or two cases in Canada imposing a similar duty in extraordinary rendition cases). Also, the arguably legal duty to provide diplomatic assistance to one's citizens doesn't apply in countries like North Korea where the U.S. has no diplomats. In practice, the U.S. government will do everything reasonably within its power to secure the release of a U.S. citizen held by a hostile foreign power (even a U.S. citizen who has behaved badly), because that's in the DNA of how the U.S. State Department always acts. But, at this point, short of an extreme Special Operations mission to abduct a prisoner that voluntarily defected from the U.S. while stationed in South Korea, there really isn't anything that the U.S. could do even if ordered to do so.
You cannot stop the claim. But the good news is that claims of jurisdiction by many countries are routinely ignored by many other countries. So enforcement attempts might fall short. I've written things here that might get me into real trouble with the authorities of North Korea if I ever traveled there and if they were able to match my real-world identity with this account. But I don't plan to travel there. Likewise, before I went to Turkey I should probably review what I've written about their government, and then wonder if it is worth the risk. Probably yes, it wasn't very incendiary. But my home country and those I tend to visit (if there is no pandemic ongoing) would not extradite me for what I wrote.
It is the job of the judge to instruct the jury about the law. If Texas had pattern instructions I'd look up what the instruction is for this matter, but you don't, so I don't know what the judge would say. But it is the judge's sole prerogative to instruct the jury in the law. If the question is a "commitment question", then it is an improper question and should be disallowed, see Stendefer v. State. The question "Would you presume someone guilty if he or she refused a breath test on their refusal alone?" is such a commitment question, and is disallowed. Similarly, "If the evidence, in a hypothetical case, showed that a person was arrested and they had a crack pipe in their pocket, and they had a residue amount in it, and it could be measured, and it could be seen, is there anyone who could not convict a person, based on that" (Atkins v. State, 951 S.W.2d 787). An improper commitment question could be of the type "could you refrain...": Let us assume that you are considering in the penalty phase of any capital murder case, okay? And some of the evidence that has come in shows that the victim's family was greatly impacted and terribly grieved and greatly harmed by the facts․Can you assure us that the knowledge of those facts would not prevent you or substantially impair you in considering a life sentence in such a case (Penry v. State, 903 S.W.2d 715). One way in which a commitment question can be legal is if it asks basically "can you uphold the law?", for example "can you consider probation in a murder case?", or "are you willing to consider mitigating circumstances". The wrong answer to those questions will lead to a for-cause dismissal. The third question is flagrantly improper, the first is rather improper, and the second probably is. If the question can be framed in terms of a candidate's willingness to follow the law, then it should be legal.
Is A or B subject to Canadian employment law? Canada and the relevant province(s) will decide in their courts if Canadian or US law applies. The USA and the relevant state(s) will decide in their courts if Canadian or US law applies. It would be open to the employee to bring an action in any relevant court; the court will then decide what law applies and if they have jurisdiction - that is part of what sovereignty means! A Canadian court can decide a matter using US law and vice-versa. Things that the court would take into consideration are if the company did business (outside this single arrangement) in Canada or was US exclusive, the number of other trans-national interns, if the arrangement was seen as a device for avoiding employment obligations in either jurisdiction. If one is subject to Canadian law then they both are. Will either party get into trouble with the Canadian government? Assuming that the arrangement is subject to Canadian law then the company would be obliged to pay wages and may be subject to fines for not having done so. If so, what enforcement (and/or punishment) mechanisms does the Canadian government have at their disposal to enforce their employment laws against A or B? B - nothing; they have not broken the law. A - an order to pay wages and fines. Enforcement may require a judgement in a US court; either by bringing the case in one the first instance or applying to have a Canadian judgement given effect in the US. Edit The OP has added the proviso that the document states that it subject to US law and jurisdiction. If it just says that, it is prima facie invalid - a contract cannot exclude the jurisdiction of any court and an attempt to do so renders it unlawful. However, if it said that it was subject to the non-exclusive jurisdiction and law of, say, Wisconsin, then a Canadian court would consider the parties intent and the relevant Canadian national and provincial law and might decide that the proper forum is a Wisconsin court and refuse to hear the complaint. Things they will consider are that there will be Canadian and provincial laws that cannot be excluded by contract, the hardship changing the forum will have on the plaintiff or defendant, if the result (assuming the facts are proven) would be demonstrably different in a US vs. a Canadian court etc.
It may simply be a case of which extradition order is deemed valid first - extradition to Sweden and to the US involve two different parts of the Extradition Act 2003, and involve different timescales. Extradition to Sweden under the European Arrest Warrant solely involves the judiciary - once all appeals have been heard and ruled on, if the extradition warrant is still deemed valid by the judiciary then the extradition must be carried out within 10 days of the final ruling. Extradition to the US involves a decision by both the judiciary and the Secretary of State - once all appeals have been heard and ruled on, if the extradition warrant is still deemed valid by the judiciary, the Secretary of State must make a determination on whether or not to allow the extradition. If the Secretary of State does determine the extradition must go ahead, then the extradition must ordinarily be carried out within 28 days of that determination. Government guidance on extraditions Thus, if both the US and Sweden put forth extradition requests, it may simply come down to which one clears all hurdles first.
You can be tried again for the same offence; double jeopardy only applies if you are found "not guilty". It is not uncommon for appeals courts to invalidate a guilty verdict and require a retrial. Similarly a mistrial can result in a new trial at the prosecution's discretion. In addition, some jurisdictions have abolished double jeopardy for crimes like murder (e.g. New South Wales, Australia). New evidence coming to light can be grounds for appeal - in the case of the Fugitive where there have been no appeals this is one avenue open to Kimble. Where appeals have been exhausted; this is more problematic. One of the principles of justice is that there should be finality to the verdict. Kimble has gone from presumed innocent to presumed guilty - enough evidence would need to be gathered to demonstrate a clear and unambiguous miscarriage of justice. This may not be within the purview of the judicial branch of government - he may need a pardon from the executive. In real life (as opposed to Hollywood) Dr. Kimble is still in serious trouble. In some jurisdictions there may be some "innocence" laws that can allow review of convictions outside the appeal process. Notwithstanding, Dr. Kimble is going away for a long time for "escaping lawful custody" anyway.
Edits added below to outline Florida's laws based on OP's comment Jurisdiction does matter but here is a general answer regarding "stand your ground" laws. States that have so-called "stand your ground laws" each have their own language concerning the law. "Stand your ground laws" are often misunderstood but, generally, just mean that a person has no duty to retreat when using deadly physical force for purposes of self-defense or the defense of others. Your examples are more akin to "castle doctrine" laws which I touch on below. Note that all of these laws vary by jurisdiction. I've provided partial examples from Arizona, New York and California. Using deadly physical force for purposes of self-defense or defense of others is complex law and even a complete example from any particular jurisdiction will not be able to cover all circumstances. Each case will be determined by a judge or jury based on the facts of that particular case. Arizona's "stand your ground" statute, as an example, states: B. A person has no duty to retreat before threatening or using deadly physical force pursuant to this section if the person is in a place where the person may legally be and is not engaged in an unlawful act. "Stand your ground" simply means that a person doesn't have to first attempt to retreat before resorting to the use of deadly force. Arizona's statute regarding justification for self-defense states (emphasis mine): A. Except as provided in subsection B of this section, a person is justified in threatening or using physical force against another when and to the extent a reasonable person would believe that physical force is immediately necessary to protect himself against the other's use or attempted use of unlawful physical force. B. The threat or use of physical force against another is not justified: In response to verbal provocation alone; or To resist an arrest that the person knows or should know is being made by a peace officer or by a person acting in a peace officer's presence and at his direction, whether the arrest is lawful or unlawful, unless the physical force used by the peace officer exceeds that allowed by law; or If the person provoked the other's use or attempted use of unlawful physical force, unless: (a) The person withdraws from the encounter or clearly communicates to the other his intent to do so reasonably believing he cannot safely withdraw from the encounter; and (b) The other nevertheless continues or attempts to use unlawful physical force against the person. Note the phrase, "extent a reasonable person." This means that the actions of a person using deadly force will be measured against what a "reasonable person" would do in similar circumstances. Some states have a duty to retreat, particularly when in a public place, before using deadly force. New York, as an example, has a "duty to retreat" before using deadly force except in specific circumstances (emphasis mine): A person may not use deadly physical force upon another person under circumstances specified in subdivision one unless: (a) The actor reasonably believes that such other person is using or about to use deadly physical force. Even in such case, however, the actor may not use deadly physical force if he or she knows that with complete personal safety, to oneself and others he or she may avoid the necessity of so doing by retreating; except that the actor is under no duty to retreat if he or she is: (i) in his or her dwelling and not the initial aggressor; or (ii) a police officer or peace officer or a person assisting a police officer or a peace officer at the latter`s direction, acting pursuant to section 35.30; or (b) He or she reasonably believes that such other person is committing or attempting to commit a kidnapping, forcible rape, forcible criminal sexual act or robbery; or (c) He or she reasonably believes that such other person is committing or attempting to commit a burglary, and the circumstances are such that the use of deadly physical force is authorized by subdivision three of section 35.20. Castle Doctrine Laws typically refer to what one may do in their own home when it comes to the use of deadly force. Some states have extended the "castle doctrine" to include personal automobiles as well. California's "castle doctrine" statute, as an example, states that if one is in their own home and someone "unlawfully and forcibly" enters the home one can presume that the person in his or her residence "held a reasonable fear of imminent peril of death or great bodily injury": Any person using force intended or likely to cause death or great bodily injury within his or her residence shall be presumed to have held a reasonable fear of imminent peril of death or great bodily injury to self, family, or a member of the household when that force is used against another person, not a member of the family or household, who unlawfully and forcibly enters or has unlawfully and forcibly entered the residence and the person using the force knew or had reason to believe that an unlawful and forcible entry occurred. As used in this section, great bodily injury means a significant or substantial physical injury. In California's statute both the resident and the person using force to gain entry have to know or have reason to believe that an unlawful and forcible entry occurred. If a person simply entered an unlocked home then the resident would have to have some other reasonable reason to believe that they were in imminent peril of death or great bodily injury. Wikipedia has a reasonable entry on the adoption of "stand your ground" and "castle doctrine" statutes and gives a state-by-state breakdown of both. Note that these laws have seen a lot of change recently and any particular entry for a state may not be accurate. Florida's self-defense laws Florida's "Use or threatened use of force in defense of person" states: 776.012 Use or threatened use of force in defense of person.— (1) A person is justified in using or threatening to use force, except deadly force, against another when and to the extent that the person reasonably believes that such conduct is necessary to defend himself or herself or another against the other’s imminent use of unlawful force. A person who uses or threatens to use force in accordance with this subsection does not have a duty to retreat before using or threatening to use such force. (2) A person is justified in using or threatening to use deadly force if he or she reasonably believes that using or threatening to use such force is necessary to prevent imminent death or great bodily harm to himself or herself or another or to prevent the imminent commission of a forcible felony. A person who uses or threatens to use deadly force in accordance with this subsection does not have a duty to retreat and has the right to stand his or her ground if the person using or threatening to use the deadly force is not engaged in a criminal activity and is in a place where he or she has a right to be. Florida outlines the cases where use, or threatened use, of force is justified. Notice that in the law Florida specifically states that the person threatened does not have a duty to retreat. Florida also specifically states that a person has a "right to stand his or her ground" if the person is in a place where he or she has a right to be and is not engaged in criminal activity. Florida statute also specifically outlines the right to use self-defense within one's home and vehicle. Florida has a "castle doctrine" similar to what was outlined above and similar in nature to New York's and California's laws: The person against whom the defensive force was used was in the process of unlawfully and forcefully entering, or had unlawfully and forcibly entered, a dwelling, residence, or occupied vehicle, or if that person had removed or was attempting to remove another against that person’s will from the dwelling, residence, or occupied vehicle; Florida has a longer list of exemptions related to who may have used force to enter a home including ownership interest in the property or vehicle, children and grandchildren, the person who engaged defensive force was involved in criminal activity and law enforcement officers. Florida's Justifiable Use Of Force is chapter 776 discusses when force can be used. There was an attempt by the Florida legislature in 2019 to change the standard by which use of force could be justified from "reasonably believes" force is necessary to "a reasonably cautious and prudent person in the same circumstances would objectively believe" force was necessary. The bill was withdrawn in May, 2019.