Sometimes the circumstantial evidence is very simple, but of a very convincing character; and sometimes the nature of the case requires the scrutiny, comparison, and interpretation of trains of circumstances which regarded separately are insufficiently criminating. As an illustration of the former sort of evidence, Lord Stowell's remark may be quoted, that "as people, according to the old saying, do not go to bawdy houses to say their paternosters, it is impossible that one can have gone to such a place for any but improper purposes;" and to have done so is universally held to be good proof of adultery. Accordingly, it has been held to be sufficient evidence of adultery, prima facie at least, that a man has gone to a brothel and shut himself into a room with a prostitute; and the same is true if a married woman goes to such a house with another man than her husband, or even alone. Of course, in both cases proof of innocence, or better of an innocent purpose, is admissible, though such evidence would not have much weight in most cases.

The mere fact that a man and woman live together in the same house, even with the common reputation of being married, while they are not so in fact, would probably not, without other suspicious circumstances, be held sufficient proof of adultery; though it would be otherwise if the parties gave themselves out to be husband and wife. With reference to cases where the intent of the defendant is less clear, and where the approaches to the act have been less bold and open, the courts have used such language as this: that it is impossible to lay down in the form of a rule what circumstances shall or shall not constitute satisfactory proof of the fact of adultery, because the same facts may constitute such proof or not, as they are modified or influenced by different circumstances. But there must be on the whole satisfactory proof that a criminal attachment or purpose existed between the parties, and that opportunities occurred when the intercourse in which it is clear that the parties intended to indulge might have taken place.

If for example, a married woman were shown by undoubted proof to have been in an equivocal position with a man not her husband, leading to a suspicion of her adultery; if it were proved that she had shown an improper fondness for the man; if they had been detected in clan-destine correspondence, had had private meetings, or made passionate declarations; if her affection had been alienated from her husband, or it appeared that her mind and heart were already depraved, and nothing was wanting but an opportunity to consummate the guilty purpose; then proof that such opportunity had occurred in connection with some or all of these other circumstances, according to the nature of the case, would lead to the satisfactory conclusion that the act had been committed. The guilty consummation, in short, may be fairly and conclusively presumed from such circumstances of conduct as, on grounds of common experience and common sense, would lead the discreet and careful judgment of a reasonable and just man to that conclusion. But, on the same principles, the conclusion may not be fairly or justly deduced, even when a witness testifies to the actual fact of adultery; for his testimony may be un-worthy of credit, either because he is mistaken or because he does not speak the truth.

On this ground the direct but uncorroborated evidence of two prostitutes as to the very act has been held insufficient proof of it; and on the same principle, the testimony even of the paramour of the defendant may require confirmation. Such a person, it has been said, is an accomplice, and all the legal considerations applicable to such a witness must be applied to him or her. Upon the same principles and within the same spirit of construction already suggested, acts in themselves rather innocent and indifferent may take the color of guilt from proof of other circumstances attending them. Thus the mere visit of a married woman to the lodgings of a single man has been held insufficient, alone, to establish criminality; but the act receives a different complexion when there is also proof of correspondence or other improper conduct between the parties. So, though a mere correspondence or intimacy with the alleged paramour would not be by itself sufficient, proof that there had been falsehood or concealment in respect to these things might justify the inference of guilt. Again, the difference between the higher and lower classes of society in their habits of life and social manners must be taken into the account in passing upon the behavior of parties in certain instances.

For indelicate acts and demeanor, which among the vulgar may be consistent with innocence, may deserve no such favorable significance when observed among those whose breeding is finer. (See Divorce.) II. The criminal offence. Adultery, by which is here meant the mere private act, is not a crime nor indictable at common law: Before the famous adultery act of 1650, in the time of the commonwealth, there was no law in England against adultery and the kindred acts as criminal offences. This statute introduced at once the utmost severity, ordaining death for incest and adultery, and three months' imprisonment for simple fornication, and making a second offence felony without clergy. The act was repealed at the restoration, and nothing was substituted in its place. Adultery, however, has been, theoretically at least, punishable in England by virtue of unwritten law in the ecclesiastical courts, though the offence has never been pursued with any great or systematic vigor; and it may be remembered that Blackstone charges the framers of the canon law with an improper levity in respect to this sort of offences from their own aptitude to commit them. In Scotland there is still, or until very recently there was, on its statute book a law making adultery and incest capital offences.

The statute, as to adultery at all events, has been long in disuse. - In many of the United States adultery is made criminal by special statutes, but in as many more it is not criminal. But though the simple act is not a crime in Ohio, Indiana, Illinois, Missouri, Louisiana, and other states, yet in many of them open and notorious adultery is criminal. The nature of the offence of adultery, created by statutes, is sometimes clearly defined by their provisions; but many of the statutes on this head simply declare the punishment of adultery, using the word as if it had a precisely ascertained meaning. In such cases it has been necessary for the courts to determine what acts were intended to be covered by the word; and upon this point has arisen an extreme diversity of opinion on account of the different views which have been taken of the policy of the law on the subject. Thus it has been sometimes said that an unmarried man's illicit intercourse with a married woman is adultery on his part, because he may impose a spurious issue upon the husband; and, upon the same ground, that a man, though married, does not commit adultery in having intercourse with an unmarried woman, because in that case there is no possibility of that result.

It has also been said that when either of the parties to the act is married, though the other is not, both commit adultery. In Massachusetts the statute expressly provides that when the crime is committed between a married woman and an unmarried man, the latter shall be deemed guilty of criminal adultery, and be liable to the punishment prescribed for that offence. The statute of Minnesota is to the same effect. In the absence of such provisions, it has been held in New Jersey, for ex-ample, that in such a case the man does not commit the crime, and in Virginia that his act is only fornication. In Connecticut the statute provides that "every man and every married woman who shall commit the crime of adultery with each other shall be punished with imprisonment." The statute of Iowa declares that when the crime is committed between persons only one of whom is married, both are guilty of adultery, and shall be punished accordingly. It seems on the whole to be the prevailing and better rule, when positive enactments do not forbid it, that when one of the parties to the act is married and the other is not, it is adultery in the married one, whether man or woman, and only fornication in the other.

From this rule results as the best definition that can be given of the offence, that criminal adultery is the voluntary sexual intercourse of a married person with another than the husband or wife; and this is the position taken by Mr. Bishop, the highest American authority on this and the cognate topics of the law. - Even though the single private act of adultery is not criminal or indictable at common law, yet within the principle that the general law will punish all acts which offend against public morality, adultery may take so gross and openly indecent a form as to be regarded as criminal at common law. But offences of this character are in general made the subject of special statutes. Such crimes, especially the living together in adultery, are not ordinarily regarded by the law as having been committed by mere occasional acts of private intercourse, but there must be proof of a general course of misbehavior, an habitual living or lodging together, though it is not impossible that the complete offence may be committed in a single day.

In several of the states it is provided that no criminal prosecution for adultery shall be commenced except on the complaint of the husband or wife of a guilty party.