Dating itself is not illegal anywhere in the United States, so a 17-year-old and a 20-year-old can spend time together, go to dinner, and hold hands without breaking a law. The real question behind whether it is illegal for a 17 and 20 year old to date is whether any sexual activity between them is legal, and that depends entirely on which state they are in. In roughly 31 states, the age of consent is 16, so a 17-year-old can legally consent. In about 7 states it is 17. In roughly 13 states and the District of Columbia, the age of consent is 18, which means sexual activity between a 17-year-old and a 20-year-old is a crime unless a specific exemption applies.1U.S. Department of Health and Human Services. Statutory Rape: A Guide to State Laws and Reporting Requirements
That state-by-state variation is the first thing to check. A relationship that is fully legal in one state can be a felony an hour’s drive across the border. Ignorance of the minor’s age is generally not a defense, and neither is the minor’s enthusiastic participation. If the state’s age of consent is 18 and no exemption applies, the 20-year-old is the one facing charges.
Where 17 Is Legal, One Big Exception Still Applies
Being in a state where 17-year-olds can legally consent does not close the question. Forty-six U.S. jurisdictions have separate statutes that raise the effective age to 18 when the older person holds a position of authority over the minor.2U.S. Department of Justice. Conflicts between State Marriage Age and Age-Based Sex Offense Teachers, coaches, tutors, school counselors, clergy, foster parents, and in some states employers of the minor all fall into this category.
So a 20-year-old who is coaching a high school team, working as a teacher’s aide, or serving as a youth group leader can commit a crime by dating a 17-year-old on that team or in that group, even in a state where 17 is otherwise the age of consent. The definitions vary. Some states list specific roles; others use broad supervisory language. The result is the same.
Close-in-Age Exemptions and the Three-Year Gap
In states where the age of consent is 18, the difference between a 17-year-old and a 20-year-old often falls inside a close-in-age exemption, sometimes called a Romeo and Juliet law. About 30 states have some version of these provisions. They typically reduce penalties or provide a complete defense when both partners are within a specified age gap, usually between two and five years, and the younger partner is at least 14.
A three-year gap between 17 and 20 fits within most of these exemptions, but not all. Some states cap the gap at two years. Some require the younger partner to be at least 16. Some exemptions are affirmative defenses the accused must raise at trial, meaning charges can still be filed and the defense mounted only in court. Others block charges from being filed at all. A handful of states have no formal exemption and rely on prosecutorial discretion.
These protections have limits worth knowing before relying on them. They never apply when force or coercion is alleged. They do not always block sex offender registration. And they do nothing to shield anyone from federal charges.
Sexting Is the Trap Most Couples Do Not See
This is where a 17-and-20 relationship most often becomes a criminal matter, even in states where the sexual relationship itself is legal. Federal law criminalizes the production, distribution, receipt, or possession of any sexually explicit image of a person under 18. It does not matter that the 17-year-old took the photo themselves or sent it willingly. A first offense for distributing such material carries a mandatory minimum of five years in federal prison and a maximum of 20. A second offense doubles the minimum to 15 years.3Office of the Law Revision Counsel. 18 USC 2252 – Certain Activities Relating to Material Involving the Sexual Exploitation of Minors
Federal prosecutors rarely pursue two people in a relationship exchanging photos, but state prosecutors are less restrained. About half the states have specific sexting statutes that route this behavior into misdemeanor charges or juvenile diversion. In states without those laws, a 20-year-old with a nude photo of their 17-year-old partner on their phone can technically face the same charges as an adult trafficking exploitative material.
The TAKE IT DOWN Act, signed into federal law in May 2025, adds a separate offense for the nonconsensual publication of intimate images, including AI-generated ones, with enhanced penalties of up to three years in prison when the person depicted is a minor. Sharing an ex-partner’s intimate image, in other words, is now its own federal crime even setting aside the child pornography statutes.
Crossing State Lines Changes the Analysis
State legality does not protect anyone who travels. Under 18 U.S.C. § 2423, knowingly transporting anyone under 18 across state lines with the intent that they engage in sexual activity that would violate any criminal law carries a mandatory minimum of 10 years in federal prison and a maximum of life.4Office of the Law Revision Counsel. 18 USC 2423 – Transportation of Minors The trip itself is the crime.
A related statute, 18 U.S.C. § 2421, covers transporting any person across state lines for sexual activity that violates criminal law, with penalties of up to 10 years.5Office of the Law Revision Counsel. 18 USC 2421 – Transportation Generally Federal jurisdiction also covers federal lands, military installations, and Indian country, where 18 U.S.C. § 2243 sets the age of consent at 16 with an additional requirement that the older partner be at least four years older. A 20-year-old and a 17-year-old fall inside that four-year window, so the federal-property statute does not itself criminalize their activity, but the state’s own law still governs everything off federal land.6Office of the Law Revision Counsel. 18 USC 2243 – Sexual Abuse of a Minor or Ward
What a Conviction Actually Costs
Statutory rape convictions carry prison time in every state, with sentences that climb as the age gap widens and the minor’s age drops. A conviction almost always triggers mandatory sex offender registration under the federal Sex Offender Registration and Notification Act.7Office of the Law Revision Counsel. 34 USC 20911 – Relevant Definitions, Including Amie Zyla Expansion of Sex Offender Definition Registration restricts where you can live, since many jurisdictions bar residency near schools and parks. It limits employment. It follows you into every state where you live, work, or attend school.8SMART Office, Office of Justice Programs. SORNA In Person Registration Requirements
The exposure does not end when the relationship does. Statutes of limitations for sexual offenses against minors are extremely long in most states, and some states have eliminated them for these offenses. The minor is not the person who decides whether charges are brought. Prosecutors can act on a report from a parent, a school counselor, a doctor, or a mandatory reporter who learned about the relationship after the fact. Text messages, social media posts, and photos that felt harmless at the time often become the evidence.
Parents Cannot Consent for the Minor
Families sometimes assume that if the 17-year-old’s parents approve, the relationship is safe. It is not. A parent cannot consent to illegal sexual activity on behalf of their child. If the state’s law is violated, the 20-year-old is criminally liable regardless of what the parents knew or approved. Parental support may affect a prosecutor’s willingness to bring charges, but it creates no legal immunity, and a parent who is supportive today may change their mind after a breakup.
Emancipation does not solve the problem either. An emancipated minor gains many rights of adulthood, but in most states emancipation does not shift the age-of-consent analysis. That threshold is set by the statute, not by the minor’s independence.
Practical Bottom Line
Check the age of consent in the specific state where the couple lives and travels. If it is 16 or 17, general sexual activity between a 17-year-old and a 20-year-old is legal there, unless the 20-year-old holds a position of authority over the 17-year-old. If it is 18, check whether the state’s close-in-age exemption covers a three-year gap and whether it blocks charges or only provides a defense at trial. Regardless of state law, do not exchange explicit images, because federal child pornography statutes apply until the younger partner turns 18, and do not cross state lines together for sexual purposes, because the federal transportation statute overrides any state’s permissiveness.