Yes, incest is illegal in New York. The state treats it as a felony under three separate Penal Law sections, with punishment ranging from probation on the low end to 25 years in prison on the high end, plus mandatory sex offender registration for every conviction. A marriage between the covered relatives is also automatically void.
Which Family Relationships Are Covered
All three incest offenses share the same list of prohibited relatives: an ancestor and descendant (parent or grandparent with child or grandchild), siblings and half-siblings, and an uncle or aunt with a niece or nephew. The statutes reach relatives by marriage as well as by blood, so step-relationships created through marriage fall inside the law.
First cousins are not on that list. Marriage and sexual contact between first cousins are legal in New York under both the Penal Law and the Domestic Relations Law.
The Three Degrees of Incest
Third Degree
Under Penal Law 255.25, a person commits incest in the third degree by marrying or engaging in sexual contact (vaginal, oral, or anal) with someone the person knows is a covered relative.1New York State Senate. New York Code PEN 255.25 – Incest in the Third Degree This is a class E felony and is the baseline charge for consensual conduct between adult relatives.
Second Degree
Penal Law 255.26 raises the offense to a class D felony when the conduct would independently qualify as rape in the second degree against a known relative. Second-degree rape generally involves a victim under 15 or a victim incapable of consent.2New York State Senate. New York Code PEN 255.26 – Incest in the Second Degree
First Degree
Under Penal Law 255.27, incest in the first degree applies when the conduct would independently qualify as rape in the first degree against a known relative. The relevant first-degree rape provisions target victims under 11, or under 13 depending on the age gap with the perpetrator. This is a class B felony.3New York State Senate. New York Penal Law 255.27 – Incest in the First Degree
Prison Time, Fines, and Probation
Maximum prison exposure climbs sharply with each degree:4New York State Senate. New York Code PEN 70.00 – Sentence of Imprisonment for Felony5New York State Senate. New York Code PEN 70.02 – Sentence of Imprisonment for a Violent Felony Offense
- Third degree (class E felony): up to four years.
- Second degree (class D felony): up to seven years.
- First degree (class B felony): up to 25 years.
For third-degree cases, and for other class D or E felonies, the court has the option to impose a definite sentence of one year or less if it finds a longer term would be unduly harsh. Probation is also available at the third-degree level when the court concludes incarceration is unnecessary for public protection; a felony probation term runs three, four, or five years.6New York State Senate. New York Code PEN 65.00 – Sentence of Probation Probation is far less realistic at the second- and first-degree levels, which involve sexual assault of minors.
On top of prison time, any felony incest conviction can carry a fine of up to $5,000, or double the amount of any financial gain the defendant derived from the offense, whichever is higher.7New York State Senate. New York Code PEN 80.00 – Fine for Felony
Mandatory Sex Offender Registration
Every degree of incest is a registerable sex offense under Correction Law 168-a.8New York State Senate. New York Correction Law 168-A – Definitions Even a third-degree conviction that results in probation with no prison time still places the person on the registry. Registrants face residence and employment restrictions, must periodically verify their address with law enforcement, and appear on a public registry anyone can search. The registration period is set at a court hearing after conviction based on risk level and can last 20 years or life.
Incestuous Marriages Are Void
New York’s Domestic Relations Law declares that a marriage between an ancestor and descendant, siblings or half-siblings, or an uncle/aunt and niece/nephew is incestuous and automatically void. A void marriage has no legal effect from the moment it takes place, whether or not the parties knew about the relationship.9New York State Senate. New York Domestic Relations Law 5 – Incestuous and Void Marriages
Going through with the ceremony carries its own penalty separate from the felony charges. Each party can be fined between $50 and $100 and jailed for up to six months, and anyone who knowingly officiates faces the same punishment.9New York State Senate. New York Domestic Relations Law 5 – Incestuous and Void Marriages
Knowledge, Consent, and Other Defenses
The central element the prosecution must prove is knowledge. Each incest statute requires that the defendant knew the other person was a covered relative, and the standard jury instructions for third-degree incest list that knowledge as an element that must be proven beyond a reasonable doubt.10New York State Unified Court System. New York Penal Law 255.25 – Incest in the Third Degree If the defendant genuinely did not know about the family connection, that lack of knowledge is a complete defense. This matters most in cases involving adoption, unknown parentage, or other family histories where two people may not realize they are related.
A defense can also attack whether the relationship itself falls within the statute. If DNA testing or legal records show the parties are not actually related in a covered way, or if the connection is one the statute does not reach (first cousins, for example), the charge cannot stand.
What is not a defense is consent. The statutes criminalize the sexual contact itself when the parties are known relatives, and mutual agreement between adults does not change that. The prohibited element is the family relationship, not the absence of consent.