delivered the opinion of the Court.

*420 This is an action of debt-upon a duty bond., l,n^elr the act of the 20th of April, 1818. Upon the trial of the cause in the Circuit Court of Massachúsetts, the following questions arose :

1. Whether the words “ true valve," in the 11th section of the act of the 20th of April, 1818, meant the current market value of such goods at the place from which they were imported, or the true and actual cost thereof to the importer at such place.

2. Whether, if the Collector did, in fact, suspect that the goods were invoiced below the current market value thereof, at the place from which they were imported, but did not suspect that they were invoiced below the true and actual cost thereof to the importer, the Collector had a bight to direct an appraisements

8. Whether, if, in the opiniop of the Collector, there was just ground to suspect that the goods were invoiced below the current market value of the same, at the place from whence they were imported, then the said Collector had aright to direct the Same to be appraised in the manner prescribed in the 11th section of the beforementioned act of Congress.

Upon which questions the Judges of the Circuit Court were opposed in opinion, and they are brought up to this Court for decision.

It seemed to be admitted on the argument ai the bar, that the answers to these questions would depend in a great measure, if not entirely, upon a more general inquiry with respect to the basis on which the ad valorem rate of duties is to be *421 estimated ; whether upon the actual cost of the goods, or the current market.value thereof, at the place from which they were imported. That, prior to the act of 1818, ad' valm em duties were to be estimated upon the actual cost of the goods, cannot admit of a doubt. In one of the earliest acts of Congress passed on this subject in the year 1789, (2 L. U. S. 22.) this was assumed as the basis. The act declares, that the ad valorem rates of duty upon goods, wares, and merchandise, at the place of importation, shall be estimated by adding twenty per cent, to the actual cosí thereof, if imported from the Cape óf Good Hope, or from any place beyond the same, and ten per cent, on the actual cení thereof, if imported from any other place or country, exclusive of charges. In the act passed but a few days before. (2 L. U. S. 5.) after the enumeration of certain articles subject to an ad valorem■ duty, it is declared, “ that on all other goods, wares, and merchandise, five per cent, on the value thereof at the time and place of importation,’’ shall be laid. The word vahie, as here used, cannot bo understood in any other sense thaii the words actual cost, in the act pr.ssed only twenty-seven days after. It would be unreasonable to suppose that, in the former u«.t, market value was established as the basis, and in the latter a new rule introduced under the terms actual cost, with a view to any change of the basis. It is more reasonable to suppose, that value and actual cost, were intended To import the same meaning. And, in other parts of the ,laws on *422 this subject, where these terms are used in reference to the rule by which the duties are to be estimated, they are to be taken in the same genge> an(j[ to understood as a varied mode of conveying the same idea. (2 L. U. S. 22. 3 vol. ed. 185.) In the act of 1799, the same basis, actual cost, is expressly adopted as the rule by which ad valprem duties are to be estimated; (3 L. U. S. 193.) and that such was the rule previous to the act of 1818, was not denied on the argument, as it certainly could not be with the least colour of plausibility. And if this be so, there ought to be a very clear expression of the legislative will, before a rule which had governed the practice on this subject for nearly thirty years, should be considered as abolished; and a- new one adopted. And, wé think, the act of 1818, (6 L. U. S. 300.) will not justify such a conclusion. If any parts of the act, when separately considered, would seem.to warrant such a construction, the whole, when taken together, admits of no such interpretation, and would, indeed, be directly at variance with the fourth section of this act, which, in terms, adopts the rule first laid down in the act of 1789* and which has been continued in all the subsequent laws, “ that the ad valorem rates of duties, upon goods, wares, and merchandise, shall be estimated by adding twenty per cent, to the actual cost thereof, if imported from the-Cape of Good Hope, or from any island, port, or place, beyond the same, and ten per cent, on the actual cost thereof, if imported from any other place,” &c. It has been contended, however, on the *423 part of the United States, that, by the terms true value, as used in .several parts of the act of 1818, and particularly in the 11th section, it was intended to substitute the current market oalue instead of actual cost, as the basis upon which , ad valorem duties are to be estimated'. The subject matter of this section is, to provide for the detection of fraudulent invoices, and fix the rule- by which the duties are to be estimated, when the invoice price is below the áctual cost. The law requires (3 L. U. S. 437.) that the invoices of all goods imported .-into the'United States, and subject to an ad valorem duty, shall contain a true statement of the actual cost of such goods. And no entry of the' goods can be made, unless the original invoice is produced, and oath made that it contains a just and true account of the cost of such goods. (3 L. U. S. 172.) And to enforce a compliance with these injunctions, by putting into the hands of the Collectors more efficient means of 'detecting all evasions of the law, was one of the principal objects of this 11th section of the act of 1818; It requires the Collector, whenever, in his opinion, there shall be just grounds to suspect that goods, subject to an ad valorem duty, have been invoiced below their true value, at the place from which they were imported, to have them appraised. This power is, to act upon a supposed case, of fraud, attempted to be practised on the government, by making out the invoice below the actual - cost. The great object to which the attention of the Collector is directed, is to ascer *424 tain the cost, that being the basis on which the duties are to be estimated. And if the invoice is raise, proper inquiry is ag t0 ^g value of the goods, and to compare that with the invoice price. And for the purpose of ascertaining such market value, the Collector is authorized to appoint appraisers, who are sworn to report, according to the best of their knowledge and belief, the true value of the goods when purchased, at the place from whence the same were imported. The appraisers have, however, no concern with the actual cost of the goods. Their duty is confined to the valve thereof, at the place of importation. And the law has declared what shall be the effect of a variance between the value, so reported, and the invoice price. A small difference will not draw after it any penalty. The appraised value must exceed the invoice price 25 per cent, or no addition to the ratio of duty is imposed. The appraised value is of necessity assumed as the price upon which the duties are to be estimated, where the difference between that and the invoice price is 25 per cent. In that case, the invoice is deemed fraudulent, and to be laid out of view; and, of course, no evidence of the cost of the goods. And the 12th section expressly declares, that the appraised value, in such case, shall be considered the true value, upon which the duty is to be estimated. Or, in other words, so far as respects the rule by which the duties are to be ascertained, the true value, as found by the appraisers, shall be deemed tlve ac *425 tual cost. Where the appraised value shall be less than the invoice value, the duty is to be charged on the invoice value, in the same manner as if no appraisement had been made.

*420 The word “true value,” in the 11th section of the act of 1919, import the samething as actual cost.

*425 So, also, in the oath required by the 5th section of this act, true value imports, nothing more nor less than actual cost. Any other construction would place it out of the power of any man to take the oath, where the goods were purchased at a rate at all differing from the market price. The law requires the invoice to be made out according to the actual cost, and this to be sworn to ; and if true value means any thing else than actual cost, the oath could not be taken. This is not a separate and distinct oath from that which is required by the act of 1799, and which is to accompany the invoice. The act declares it to be,, not an additional oath, but facts in addition, to the oath now required by law, which addition is, that “ the invoice produced by him exhibits the true value of such goods, wares, or merchandise, in their actual state of manufacture, at the place from which the same were imported.” There can be but one invoice and one oath, and that invoice must be made out according to the actual cost, and it necessarily follows, that true value imports the same thing under a varied mode of expression. If it was permitted to make out two invoices of the same goods, one according to the actual cost, and the other according to the market value, and distinct baths' annexed to each, it might remove the difficulty *426 suggested. But that is not allowable. And no statute ought to receive a construction that will render it nugatory, or which prescribes a rule utterly,impracticable, without incurring the guilt of perjury. If, then, the basis upon which ad valorem duties are to be estimated, has not been changed by the act1 of 1818, from the actual cost to the market value of the goods at the place of importation, as we are satisfied it has not> the answer to the first question certified to this Court will be, that the words- 11 true valué ,” in the 11th section of the act of 1818, import the same thing as actual cost.

The other questions answered in the negative.

And as was conceded on the argument, dispose of the other questions, and require that they should be answered in the negative so far as, from the form in which they are propounded, they will admit of a direct answer.

In explanation, however, of this answer, it is proper to observe, that the 11th section of the act to which the questions are pointed, is intended to clothe the Collector with enlarged powers to guard agáinst fraudulent invoices. Whenever, ip his opinion, there" shall be just grounds t‘o suspect that the invoice does not. truly state the actual cost of the goods1, he may direct an appraisement. How, or by-what means, that opinion is made up, no one has authority tq inquire, or a right to control. Ordinarily, it will be found from his own knowledge, or the information he gets from others, of the market price of the goods, and if. that should differ .widely from thé invoice prices, it will afford grounds for suspect- *427 mg the-invoice to be fraudulent. For, as a general course of business, it is to be presumed that goods are purchased at the common market price. The authority of the Collector' to direct an appraisement, is regulated, hpwever, entirely by his own suspicion that the invoice is untrue, and does not state the actual cost of the goods as required by law. Whether this suspicion is well founded or not, is not matter of inquiry. So far as respects the authority of the Collector to direct the appraisement, he is governed altogether by his own opinion of the grounds of suspicion. Whether these suspicions were well or ill founded, and the consequences resulting therefrom, will depend upon after inquiry before the appraisers, and their decision thereupon. But the Collector cannot be called upon to avow, or show the grounds upon which his suspicion rests. The law has vested him with an uncontrolled discretion on this subject, to be regulated and governed by his own opinion, of the sufficiency of the grounds on which hé suspects the invoice to be below the true value or actual cost of the goods.

These answers must, accordingly, be certified to the Circuit Court, upon the questions submitted to this Court.

Certificate. This case came on to be heard on the certificate of the difference in opinion of the Judges, &c. On consideration whereof, this Court is of opinion, and directs it to be certified to the said Circuit Court, that the words “ true *428 value," in the eleventh section of the act ofCongress of the 20th of April, 1818, do mean the actual cost thereof to the importer at the place from which the same was imported ; and that the second question, upon which the opinions of the said Judges were opposed, viz. whether, if the Collector did, in fact, suspect that the goods ^were invoiced below the current market value thereof, at the place from which they .were imported, but did not,suspect that they were invoiced below the true and actual cost thereof to the importer, the Collector had a right to direct an appraisement ? be answered in the negative ; and do also direct it to be certified, that the third question, on which the opinions of the said Judges were opposed, viz..whether, if, in the opinion of the Collector, there was just ground to suspect that the goods were invoiced below the current market value of the same, at the place from whence they were imported, then the said Collector had a right to direct the same to be appraised in the manner prescribed in the eleventh section of the before mentioned act of Congress? be likewise answered negativelv.