Federal law makes it criminal to engage in a sexual act with another person who is between the age of 12 and 16 if they are at least four years younger than you. Each state takes a different approach as the age of consent has ranged from 10 to 18. Some states, such as California and New York, set an age at which all sexual intercourse is considered statutory rape. For example, a state might set the age of consent at 18. In this hypothetical state, two seventeen-year-olds who had consensual sex could both theoretically be convicted of statutory rape.
Other states imply a different method which, like the federal statute, takes into account the relative ages of both people. In these states, such as Texas, the age of consent is determined by age differentials between the two persons and limited by a minimum age. For example, a state might set a minimum age of 14 but limit consent to partners who are within 3 years of their age. This would allow a sixteen-year-old to lawfully have sex with a fourteen-year-old, but make it criminal for an eighteen-year-old to have sex with that same fourteen-year-old.
Examples of different state’s statutory ages of consent:
California – The age of consent in California is 18. It is illegal for anyone to engage in sexual intercourse with a minor (someone under the age of 18), unless they are that person’s spouse. California employs a tiered system where the greater the difference in age, the greater the penalty. If the person engaging in sex with a minor is less than 3 years older or younger than the minor, then they are guilty of a misdemeanor. If they are more than 3 years older than the minor then they are guilty of a felony. Those over the age of 21 engaging in sex with those under 16 are subjected to more harsh penalties.
Florida – The age of consent in Florida is 18. It is illegal for anyone over the age of 24 to have sex with anyone under the age of 18, unless they are married.
Illinois – The age of consent in Illinois is 17. For people 18 or over, it is illegal for them to commit acts of a sexual nature on persons who are under the age of 18 if they are in a position of authority or trust over the victim. This effectively raises the age of consent for older people in positions of authority or trust to 18 years old.
New York – The age of consent is 17. It is illegal for anyone to have sex with someone under the age of 17.
Texas -The age of consent is 17. The minimum age is 14 with an age differential of 3 years; thus, those who are at least 14 years of age can legally have sex with those less than 3 years older.
Alaska: Consent is at 16, but is it still illegal for adults to have sex with minors (under 18).
Louisiana: There is no definite age of when a minor may consent to sex in Louisiana. ... A person between the ages of 13 and 15 can consent to have sex with someone who is up to 3 years older than them, but a person between the ages of 15 and 17 may consent to sex only if the other person is 2 years older or less.
Many more laws. Essentially I was trying to say that some states take age differentials into account to determine legality.