Charging an 18 year old with stat rape of a 16 year old is insane. These charges are designed for hebephiles taking advantage of teenagers, not teenagers having sex with their girlfriends.
Hell, a 16 year old girl is likely more emotionally mature and in a better position to make these kinds of decisions than an 18 year old boy.
source: http://www.sexlaws.org/california_statutory_rape_laws
1. Q: What is the legal age of consent to have sexual intercourse in California?
A: 18 years old. This means sexual contact with a minor under the age of 18 is illegal in the state of California even if the minor says it is consensual.
2. Q: What is the California statutory rape law?
A: The California statutory rape law is titled "Unlawful Sexual Intercourse" Section 261.5
California Penal Code: Section 261.5 Unlawful Sexual Intercourse
Section 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 21 years of age or older 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.