According to California law, a person turns 18 years old at 12:01 a.m.
Your partner was under 18 at the time of the offense. 
In prior case law, the courts have found that this does not excuse cases where the partner was married to someone else.
You and the other person were not married at the time. California law defines sexual intercourse as any amount of bodily penetration, even if there was no ejaculation.
You had sexual intercourse with another person. In order to convict you of statutory rape, a prosecutor must prove three things happened:
Defenses Against Statutory Rape ChargesĬalifornia Penal Code 261.5 PC defines statutory rape as a case of someone above the age of consent (18) having sex with an unmarried partner who is below the age of consent. Does a Statutory Rape Conviction Require Me To Register As a Sex Offender?. 
Does California Have a ‘Romeo and Juliet’ Law?. What is the age of consent in California?.