CH. V.]
RULES OF INTERPRETATION.
433
other purpose in the acknowledged exercise of a very different power. Congress may make that a regulation of commerce, which a state may employ as a guard for its internal policy, or to preserve the public health or peace, or to promote its own peculiar interests.[1] These rules seem clearly deducible from the nature of the instrument; and they are confirmed by the positive injunctions of the tenth amendment of the constitution.
§ 448. XIII. Another rule of interpretation deserves consideration in regard to the constitution. There are certain maxims, which have found their way, not only into judicial discussions, but into the business of common life, as founded in common sense, and common convenience. Thus, it is often said, that in an instrument a specification of particulars is an exclusion of generals; or the expression of one thing is the exclusion of another. Lord Bacon's remark, "that, as exception strengthens the force of a law in cases not excepted, so enumeration weakens it in cases not enumerated," has been perpetually referred to, as a fine illustration. These maxims, rightly understood, and rightly applied, undoubtedly furnish safe guides to assist us in the task of exposition. But they are susceptible of being applied, and indeed are often ingeniously applied, to the sub version of the text, and the objects of the instrument. Thus, it has been suggested, that an affirmative provision in a particular case excludes the existence of the like provision in every other case; and a negative provision in a particular case admits the existence of the same thing in every other case.[2] Both of these deductions are, or rather may be, unfounded in solidvol. i.55
