Under 18 is statutory rape. Here is the CA Penal Code and some other info:
PENAL CODE
SECTION 261-269
261.5. (a) Unlawful sexual intercourse is an act of sexual
intercourse accomplished with a person who is not the spouse of the
perpetrator, if the person is a minor.
For the purposes of this section, a "minor" is a person
under the age of 18 years and an "adult" is a person
who is at least 18 years of age.
(b) Any person who engages in an act of unlawful sexual
intercourse with a minor who is not more than three years
older or three years younger than the perpetrator, is
guilty of a misdemeanor.
(c) Any person who engages in an act of unlawful sexual
intercourse with a minor who is more than three years younger than
the perpetrator is guilty of either a misdemeanor or a felony, and
shall be punished by imprisonment in a county jail not exceeding one
year, or by imprisonment in the state prison.
(d) Any person over the age of 21 years who engages in an act of
unlawful sexual intercourse with a minor who is under 16 years of age
is guilty of either a misdemeanor or a felony, and shall be punished
by imprisonment in a county jail not exceeding one year, or by
imprisonment in the state prison for two, three, or four years.
(e) (1) Notwithstanding any other provision of this section, an
adult who engages in an act of sexual intercourse with a minor in
violation of this section may be liable for civil penalties in the
following amounts:
(A) An adult who engages in an act of unlawful sexual intercourse
with a minor less than two years younger than the adult is liable for
a civil penalty not to exceed two thousand dollars ($2,000).
(B) An adult who engages in an act of unlawful sexual intercourse
with a minor at least two years younger than the adult is liable for
a civil penalty not to exceed five thousand dollars ($5,000).
(C) An adult who engages in an act of unlawful sexual intercourse
with a minor at least three years younger than the adult is liable
for a civil penalty not to exceed ten thousand dollars ($10,000).
(D) An adult over the age of 21 years who engages in an act of
unlawful sexual intercourse with a minor under 16 years of age is
liable for a civil penalty not to exceed twenty-five thousand dollars
($25,000).
(2) The district attorney may bring actions to recover civil
penalties pursuant to this subdivision. From the amounts collected
for each case, an amount equal to the costs of pursuing the action
shall be deposited with the treasurer of the county in which the
judgment was entered, and the remainder shall be deposited in the
Underage Pregnancy Prevention Fund, which is hereby created in the
State Treasury. Amounts deposited in the Underage Pregnancy
Prevention Fund may be used only for the purpose of preventing
underage pregnancy upon appropriation by the Legislature.
261.6. In prosecutions under Section 261, 262, 286, 288a, or 289,
in which consent is at issue, "consent" shall be defined to mean
positive cooperation in act or attitude pursuant to an exercise of
free will. The person must act freely and voluntarily and have
knowledge of the nature of the act or transaction involved.
A current or previous dating or marital relationship shall not be
sufficient to constitute consent where consent is at issue in a
prosecution under Section 261, 262, 286, 288a, or 289.
Nothing in this section shall affect the admissibility of evidence
or the burden of proof on the issue of consent.
261.7. In prosecutions under Section 261, 262, 286, 288a, or 289,
in which consent is at issue, evidence that the victim suggested,
requested, or otherwise communicated to the defendant that the
defendant use a condom or other birth control device, without
additional evidence of consent, is not sufficient to constitute
consent.
Updates 04-2001:
From District Attorney (
http://www.stanislaus-da.org/statutory_rape.htm)
What is Statutory Rape?
Statutory Rape is unlawful sexual intercourse with someone
under the age of 18.
What is Vertical Prosecution?
Vertical Prosecution means one prosecutor handling the
case from issuance to final disposition. Studies show that
when it comes to crimes of a personal and sexual nature one
attorney handling all aspects of the case, from charging
through sentencing, increases effectiveness in
understanding the dynamics of each particular case and the
needs of each victim.
Do WE PROSECUTE EVERY CASE?
No. We are evaluating each case independently to determine if
criminal charges are appropriate.
WHY SO MUCH ATTENTION TO STATUTORY RAPE?
California has the highest teen birth rate in the U.S.
Every 8 minutes, a teenager in California has a baby.
3 of 4 births to High School girls are fathered by adults.
Men over 25 account for twice as many teen births as boys under 18 years old.
The Average Age difference between the teen victim and the adult defendant in cases filed by the District
Attorney is 7years 9months.
Men over 20 are responsible for 5 times as many births among junior high school girls.
In California almost 70% of teen births are fathered by adult men.
On an average California day 76 teenage girls, 17 & younger, will give birth.