But there are many cases in which the problem is not so simple, and where the state regulations are so important that their violation should not be permitted under the cloak of federal sanction. Particularly is this true where the detention of a postal employee is, superficially, forbidden under the federal statutes, and there arises the dilemma that either the governmental agent is immune from interference while in discharge of his duties and at all times for acts committed in the course of his employment, or that the national regulations must give way.

For example, from the beginning of congressional activity under the postal power, there has constantly been a prohibition, under severe penalties, of any obstruction of the mail. The federal district court for Maryland considered a case where stage horses upon which an innkeeper had a lien were stopped in the public highway while driving a coach containing the mail. The court held that since the United States could not be sued, “the defendant could not justify the stopping of the mail on principles of common law, as they apply to individuals and to the government.” But, further, the defendant was not justifiable under the act of Congress which introduced no exception. “Whether the acts which it prohibits to be done were lawful or unlawful before the operation of that law, or independent of it, might or might not be justified, is not material. This law does not allow any justification of a wilful and voluntary act of obstruction to the passage of the mail. If, therefore, courts or juries were to introduce exceptions not found in the law itself, by admitting justifications for the breach of the act, which justifications the act does not allow to be made, it would be an assumption of legislative power.”[370]

And when a warrant in a civil suit was served on a mail carrier and he was detained thereby, Chief Justice Taney (on circuit) held that the warrant was not justification to the traverser, a constable, yet the mere serving “would not render the party liable, to an indictment under this law. But if, by serving the warrant, he detained the carrier, he would then be liable.”[371] Here also the immunity was simply as to civil proceedings.

But when a carrier, while discharging his duty, was arrested upon an indictment for murder, and it was argued that this was an obstruction of the mail within the federal statute, the Supreme Court refused to listen to the plea, and held that the law, “by its terms applies only to persons who ‘knowingly and wilfully’ obstruct the passage of the mail or of its carrier; that is, to those who know that the acts performed will have that effect and perform them with the intention that such shall be their operation. When the acts which create the obstruction are in themselves unlawful, the intention to obstruct will be imputed to their author, although the attainment of other ends may have been his primary object. The statute has no reference to acts lawful in themselves, from the execution of which a temporary delay to the mails unavoidably follows. All persons in the public service are exempt, as a matter of public policy, from arrest upon a civil process while thus engaged. Process of that kind can, therefore, furnish no justification for the arrest of a carrier of the mail.... The rule is different when the process is issued upon a charge of felony. No officer or employee of the United States is placed by his position, or the services he is called to perform, above responsibility to the legal tribunals of the country, and to the ordinary processes for his arrest and detention when accused of a felony, in the forms prescribed by the Constitution and laws.

“The public inconvenience which may occasionally follow from the temporary delay in the transmission of the mail caused by the arrest of its carriers on such charges is far less than that which would arise from extending to them the immunity for which the counsel of the government contends. Indeed, it may be doubted whether it is competent for Congress to exempt the employees of the United States from arrest on criminal process from the state courts when the crimes charged against them are not merely mala prohibita but are mala in se. But whether such legislation of that character be constitutional or not, no intention to extend such exemption should be attributed to Congress unless clearly manifested by its language.”[372]

Thus, the Supreme Court of Maine decided that a mail carrier, while in the performance of his duties, is liable to arrest for an offense against the law of the state, even though it be not a felony but a violation of a liquor regulation, and the public employment of the carrier will not justify him in assaulting the officer who serves the warrant.[373] It was held, further, that preventing a horse from being taken from the stable for the purpose of carrying the mail was no offense under the federal law since the mail had to be in transitu.[374]

The attachment, knowingly, of a coach carrying the mail is void, being an obstruction;[375] but levy on and sale of a ferryboat used to carry the mail do not constitute an obstruction.[376] In United States v. De Mott[377] it was held that the statute “is applicable to a person stopping a train carrying the United States mail, although he has obtained a judgment and writ of possession from a state court against the railroad company in respect to lands about to be crossed by such train.” It is, moreover, not a sufficient plea to an indictment for obstructing the mails, that the defendant was required by state law to collect tolls in advance from all drivers of wagons. “It is not the right of the company to the tolls under the state law which is doubted,” said the Court, “but the right to stop the passage of the mails to enforce their collection which is denied.”[378]

The rule may thus be stated to be as follows: In order to guard against obstruction of the mails, postoffice employees, while in discharge of their duty, have immunity from interference on civil processes, but are liable for felonies, and perhaps, misdemeanors. But a different and more serious question upon which these cases throw little or no light, is presented when a postal agent in the discharge of a duty imposed by federal law (neglect of duty being punishable) thereby performs an act which has been made criminal by the state.[379] There are, naturally, but few cases when this conflict arises, but it is entirely possible, perhaps the most favorable opportunity being when a postmaster distributes certain mail matter, the possession or dissemination of which the state has declared unlawful. This conflict was once presented very acutely.

In the senatorial debate on Calhoun’s bill to deal with incendiary publications in the mails, the federal question of interference with the freedom of the press received the greatest attention[380] and the equally important question of the validity of state legislation was only meagrely considered. Nearly all of the Southern States had extremely stringent laws, making the publication, circulation and even the possession of objectionable literature punishable by severe penalties. Postal officials were not exempted; in Virginia they were specifically included.[381] Nevertheless, the objectionable dissemination continued, and Amos Kendall, postmaster general, who had left the problem largely in the hands of local officers,[382] was importuned from many sources to take decisive action. The citizens of Petersburg, Va., on August 8, 1835, petitioned him to “adopt such lawful regulations in his department as may be calculated to prevent” the dissemination of incendiary papers. More elaborate resolutions were adopted at Richmond, and at Charleston it was declared:

“That the postoffice establishment cannot consistently with the Constitution of the United States and the objects of such an institution, be converted into an instrument for the dissemination of incendiary publications, and that it is the duty of the federal government to provide that it shall not be so prostituted, which can easily be effected by merely making it unlawful to transport by the public mail, through the limits of any state, any seditious papers, forbidden by the laws of such state, to be introduced or circulated therein, and by adopting the necessary regulations to effect the object.” The resolutions then went on to assert “the right of each state to provide by law against the introduction of a moral pestilence, calculated to endanger its existence, and to give authority to their (sic) courts adequate to the suppression of the evil.”[383]