See Mitchell vs. Harmony, 13 How. 115 (1851)
The 2d and 3d objections will be considered together, as they depend on the same principles. Upon these two grounds of defence the Circuit Court instructed the jury, that the defendant might lawfully take possession of the goods of the plaintiff, to prevent them from falling into the hands of the public enemy; but in order to justify the seizure the danger must be immediate and impending, and not remote or contingent. And that he might also take them for public use and impress them into the public service, in case of an immediate and pressing danger or urgent necessity existing at the time, but not otherwise.* * *
If the power exercised by Colonel Doniphan had been within the limits of a discretion confided to him by law, his order would have justified the defendant even if the commander had abused his power, or acted from improper motives. But we have already said that the law did not confide to him a discretionary power over private property. Urgent necessity would alone give him the right; and the verdict finds that this necessity did not exist. Consequently the order given was an order to do an illegal act; to commit a trespass upon the property of another; and can afford no justification to the person by whom it was executed. The case of Captain Gambier, to which we have just referred, is directly in point upon this question. And upon principle, independent of the weight of judicial decision, it can never be maintained that a military officer can justify himself for doing an unlawful act, by producing the order of his superior. The order may palliate, but it cannot justify.
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We do not understand that any objection is taken to the jurisdiction of the Circuit Court over the matters in controversy. The trespass, it is true, was committed out of the limits of the United States. But an action might have been maintained for it in the Circuit Court for any district in which the defendant might be found, upon process against him, where the citizenship of the respective parties gave jurisdiction to a court of the United States. The subject was before this court in the case of McKenna v. Fisk, reported in 1 How. 241, where the decisions upon the question are referred to, and the jurisdiction in cases of this description maintained.
"The Fourth Circuit’s ruling also is entirely inconsistent with this Court’s long experience with the review of Executive branch seizures. In Mitchell v. Harmony, this Court reviewed and rejected the military’s seizure of a citizen’s property in Mexico during the Mexican-American war. 54 U.S. (13 How.) at 128-29. The plaintiff, a naturalized American businessman, filed an action against a U.S. colonel to recover the value of his property seized by the military. The government responded that the businessman had a “design” to trade with the enemy, and that the decision of the military commander to seize the property “must be entitled to some respect.” Id. at 118, 120.
"Rejecting these arguments, Chief Justice Taney’s opinion for the Court found the government’s defense to be based on “rumors which reached the commanding officer.” Id. at 133. “Mere suspicions of an illegal intention,” the Court stated, “will not authorize a military officer to seize and detain the property of an American citizen. The fact that such an intention existed must be shown; and of that there is no evidence.” Id. If an Article III court, consistent with separation of powers principles, can inquire into the seizure of a citizen’s property by the military within a country at war with the United States as in Harmony, these same principles surely pose no barrier to an inquiry into the seizure of the citizen himself."
It seems that Mitchell is not applicable to the situation of the South in the ACW. By their insurrection, the southern rebels forsook their claim to United States citizenship. I do not see how they could assert legal protections, if those protections were even applicable, from the document and country they renounced.