SIR,--The President is informed through the channel of a letter from yourself to Mr. Lear, that M. Duplaine, consul of France at Boston, has lately, with an armed force, seized and rescued a vessel from the officer of a court of justice, by process from which she was under arrest in his custody: and that he has in like manner, with an armed force, opposed and prevented the officer, charged with process from a court against another vessel, from serving that process. This daring violation of the laws requires the more attention, as it is by a foreigner clothed with a public character, arrogating an unfounded right to admiralty jurisdiction, and probably meaning to assert it by this act of force. You know that by the law of nations, consuls are not diplomatic characters, and have no immunities whatever against the laws of the land. To put this altogether out of dispute, a clause was inserted in our consular convention with France, making them amenable to the laws of the land, as other inhabitants. Consequently, M. Duplaine is liable to arrest, imprisonment, and other punishments, even capital, as other foreign subjects resident here. The President therefore desires that you will immediately institute such a prosecution against him, as the laws will warrant. If there be any doubt as to the character of his offence, whether of a higher or lower grade, it will be best to prosecute for that which will admit the least doubt, because an acquittal, though it might be founded merely on the opinion that the grade of offence with which he is _charged_ is higher than his _act_ would support, yet it might be construed by the uninformed to be a judiciary decision against his amenability to the law, or perhaps in favor of the jurisdiction these consuls are assuming. The process therefore, should be of the surest kind, and all the proceedings well grounded. In particular, if an arrest, as is probable, be the first step, it should be so managed as to leave room neither for escape nor rescue. It should be attended with every mark of respect, consistent with safe custody, and his confinement as mild and comfortable also, as that would permit. These are the distinctions to which a consul is entitled, that is to say, of a particular decorum of deportment towards him, indicative of respect to the sovereign whose officer he is. The President also desires you will immediately obtain the best evidence it shall be in your power to procure, under oath or affirmation, of the transaction stated in your letter, and that in this, you consider yourself as acting as much on behalf of M. Duplaine as the public, the candid truth of the case being exactly that which is desired, as it may be the foundation of an act, the justice of which should be beyond all question. This evidence I shall be glad to receive within as few days, or even hours, of delay as possible.