Adultery and Fornication Statutes in Illinois

This article is not a substitute for legal advice; if you are faced with a legal issue you should speak with an attorney who can consider your particular circumstances and properly advise you. The citations contained in this article have been removed prior to publication; if you are interested in the sources used, please feel free to contact the author directly.

Recently, Jaleel Law P.C. published an article regarding Illinois statutes against adultery and fornication. Archaic laws are inherently interesting, and the article inspired me to write my own essay on the topic. With that said, let us take a look at what these criminal statutes are, and what purpose they might serve today.

Tools of the Trade

Adultery and fornication are two very similar offences contained within the Illinois Criminal Code. Interestingly, adultery is considered a graver offence and is punishable by twice as much jail time. The Committee Comments to the Criminal Code indicate that adultery is more serious because it “involves an affront to a specific marriage relationship, in addition to an affront to the institution of marriage in general.” On a happier note, it has been policy at times to forgive acts of adultery and fornication when the parties subsequently marry one another (please remember, however, that bigamy is still a crime in Illinois).

Adultery is a Class A misdemeanour and punishable by up to 364 days in jail. A person commits adultery when they have sexual intercourse with another who is not their spouse, and the behaviour is open and notorious. Additionally, at least one of the people involved in the sexual intercourse must be married, and the defendant must have knowledge of this fact.

Fornication is a Class B misdemeanour, and may be punished by up to 180 days in jail. Again, the offence is committed when one person has sexual intercourse with another who is not their spouse, and the behaviour is open and notorious. Unlike adultery, there is no additional element regarding one of the participants being married.

In the past, both statutes were quite different. They focused on co-habitation rather than specific acts of sexual intercourse, and only spoke about living in an “open state” of adultery or fornication. In 1961, the statutes were amended, and the “open and notorious” language came into effect the next year. By the 70s, the statutes resembled what we have now; they allowed particular acts of sexual intercourse to be charged, rather than co-habitation, and used the “open and notorious” language.

If you are reading this, then you likely have some notion of what “sexual intercourse” involves. However, the phrase “open and notorious” is not so clear. To begin with, it is important to stress that the behaviour must be both “open” and “notorious”. Courts have interpreted the “open” to refer to the actions of the offender, and the “notorious” to refer to the subsequent public knowledge. Importantly, that means it is not sufficient that the public merely know about the illicit relationship; rather, it must be shown that the offender flaunted the relationship (open), thus creating public knowledge (notorious).

In terms of applying the law to specific fact patterns, one can imagine countless ways in which an offender might carry out an open and notorious relationship. The Illinois Appellate Court has published a handful of opinions on the matter, but it will suffice for this article to examine the 1975 case of People v. Cessna. This case is instructive because it was decided under a statute closely resembling the current version, and it specifically involved the definition of “open and notorious”.

In Cessna, the defendant was charged with adultery, fornication, and contributing to the sexual delinquency of a child. The fornication charge was apparently dismissed short of trial, but defendant was convicted of the remaining two crimes. On appeal, defendant challenged in part whether the People had proven that his illicit relationship was “open and notorious”; the facts are as follows.

Defendant was a married 23 year old who separated from his wife. Defendant moved in with his mother in Illinois. During the month of October, 1974, a 17 year old woman met defendant, and on several occasions spent the night at his house. The 17 year old was between homes, variously living at her sister’s house, her aunt’s house, and a foster home. Defendant and the woman had sexual intercourse on several occasions, and the woman’s family saw the two of them in each other’s company. Defendant gave the woman an engagement ring, and the woman’s father heard from an attorney that defendant had discussed divorcing his wife and marrying the woman. The woman was apparently also pregnant.

According to the defendant and his family, the woman only slept over twice. Furthermore, they indicated that the defendant slept in a separate bedroom from the woman. The defendant denied having sexual intercourse with her. The court, however, found the woman’s testimony regarding the sexual intercourse to be “clear and convincing”.

The Illinois Appellate Court found that the above behaviour was not open and notorious, because there was no showing that defendant’s behaviour had created a public scandal. The evidence did not show that people outside of the two families knew about the relationship. While it was indeed a “situation of serious family concern”, the court stated that without the community being “debased or demoralized” there could be no conviction.

In rendering its decision, the court held that “[t]he prohibition of open and notorious adultery is meant to protect the public from conduct which disturbs the peace, tends to promote breaches of the peace, and openly flouts accepted standards of morality in the community. [] What is of marked interest is the scandalous effect of the behavior and its affront to public decency and the marital institution.” Had there been evidence of people outside the family circle being aware of this behaviour, the result may well have been different. In any event, defendant’s conviction for adultery was reversed, and the conviction for contributing to the sexual delinquency of a child was affirmed.

Practical Applications

It is one thing to understand a particular crime, and another to know how it might be applied. The statutes have an obvious utility in the criminal field, but as with all criminal offences they are relevant in a wide range of proceedings and situations. A criminal conviction is a serious matter, and courts in areas such as immigration and family law have referred to the statutes.

Spirit of the Law

Fundamentally, there is the most obvious use of the statutes: to prevent and punish acts of adultery and fornication. However, this is perhaps their most unlikely use. Courts have noted that these crimes are rarely charged, and members of the public might consider the statutes archaic and unsuitable. Additionally, institutions do not generally train people to use these statutes, so attorneys and officers may be unaware of their continued existence and viability. Finally, with the prevalence of bench trials, the judiciary would also need to exhibit a willingness to find people guilty of these offences. Without a shift in focus, ideals, and training throughout the entire system, it seems unlikely that these two statutes will be resurgent in their own right.

Charging Instrument

In parts of this country, the prosecutor’s office must approve of certain cases before the suspect may be charged with a felony. If a prosecutor rejects the felony charge, the police officer may still initiate a misdemeanour case. This rejected felony will then land on a misdemeanour call and be taken up by a new prosecutor. Therefore, procedurally, the police may use the adultery and fornication statutes to initiate a prosecution for a sex crime that has been rejected by Felony Review.

The adultery and fornication statutes are particularly relevant because there are few misdemeanours that specifically outlaw sex crimes. The misdemeanour criminal sexual abuse statute can only be charged when the people involved are within a strict age range. Misdemeanour battery, another option, is an awkward fit because the language was not written to deal specifically with sexual intercourse and consenting partners. Public indecency requires that the sex take place out in public. There are others, too, but ultimately adultery and fornication contain a unique set of elements that afford officers additional charging options.

Case Disposition

When resolving a case with a plea, different criminal statutes have different effects. For example, a criminal sexual abuse plea will involve sex offender registry, while certain types of battery do not allow defendants to receive day-for-day credit. Adultery and fornication, whilst seldom used, present a unique set of opportunities for resolving a case.

Neither adultery nor fornication require the defendant to register as a sex offender. Absent a specific finding from the court, they do not bar a person from receiving day for day credit. Furthermore, fornication is only a Class B offence; both battery and criminal sexual abuse are Class A offences. Finally, because adultery and fornication contain a unique set of elements, they suit fact patterns that are not encompassed by the other statutes.

Other Fields

Adultery and fornication statutes may further have significance outside the criminal law field. In the past, Illinois courts have referred to the statutes in family law proceedings to help determine such issues as child custody. The statutes have a history in immigration law, too; in 1948, the United States Supreme Court held that adultery contradicted the notion of “good moral conduct” when considering an application for citizenship. What significance the laws have today in such fields, I cannot say; hopefully attorneys experienced in those fields will join the discussion.


As shown above, the statutes outlawing adultery and fornication are more complicated than one might expect. They present a unique set of elements, and the results of a conviction are different compared to certain other misdemeanours. People willing to think outside the box may use these archaic laws to bring forward and resolve cases in new ways.

I hope others out there will be able to share their own experiences and thoughts. Similar to counsel at Jaleel Law, I have not seen anybody charged initially with either of these two offences. What will happen with these statutes in the future, one can only imagine.

This article was originally posted in 2015

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