Sec.8.  The next power of congress is, “to exercise exclusive legislation over such district, not exceeding ten miles square, as may, by cession of particular states, and the acceptance of congress, become the seat of government of the United States.”  If the seat of the general government were within the jurisdiction of a state, congress and other public officers would be dependent on the state authority for protection in the discharge of their duties.  To guard the public business more effectually against the danger of interruption, complete and exclusive power at the seat of government is given to congress.  The old congress had once, near the close of the Revolution, been treated with insult and abuse while sitting at Philadelphia; and the executive authority of Pennsylvania having failed to afford protection, congress adjourned to Princeton in the State of New Jersey.

Sec.9.  It appears that the cession of this territory to the general government had not yet been made; but it was in contemplation by the states of Virginia and Maryland to cede it.  It is called the District of Columbia.  Its inhabitants are subject to the laws of congress.  That part of the district which was ceded by Virginia, was in 1846, retroceded by congress to that state.  To congress is given, with equal propriety, exclusive authority over all places purchased “for the erection of forts, magazines, arsenals, dock-yards, and other needful buildings.”

Sec.10.  The last power granted in this section, is the power “to make all laws which shall be necessary and proper for carrying into execution the foregoing powers, and all other powers vested by this constitution in the government of the United States, or in any department or officer thereof.”  As it was impossible to enumerate in the constitution every particular act which congress might find it necessary to perform, certain powers were expressly granted; and to these powers was added this general grant of power to pass laws for carrying them into effect.

Sec.11.  It is the opinion of eminent statesmen that this clause confers no additional power.  They hold that the power therein granted is necessarily implied or included in the foregoing powers.  For example:  The power “to regulate commerce” includes the power to cause the construction of break-waters and light-houses, the removal of obstructions from navigable rivers, and the improvement of harbors; for in regulating and facilitating commerce, these works and improvements are absolutely necessary.  So the power “to establish post-offices” implies the power to punish persons for robbing the mail.  The doctrine is, “that wherever a general power to do a thing is given, every particular power for doing it is included.”  Hence it is inferred that congress would have had the power to pass the laws here authorized, though no express power for that purpose had been given.

Sec.12.  Besides the long list of powers contained in the eighth section of the first article of the constitution, and considered in preceding chapters, there are sundry other powers of congress in subsequent articles, which will be noticed in their order.