Here is the Utah state law, as is applicable to statutory rape in Utah. The URL is Age Of Sexual Consent Laws For Utah; Statutory Rape Laws For Utah. (Scroll about halfway down the page for the specific links.)
76-5-401. Unlawful sexual activity with a minor -- Elements -- Penalties -- Evidence of age raised by defendant.
(1) For purposes of this section "minor" is a person who is 14 years of age or older, but younger than 16 years of age, at the time the sexual activity described in this section occurred.
(2) A person commits unlawful sexual activity with a minor if, under circumstances not amounting to rape, in violation of Section 76-5-402, object rape, in violation of Section 76-5-402.2, forcible sodomy, in violation of Section 76-5-403, or aggravated sexual assault, in violation of Section 76-5-405, the actor:
(a) has sexual intercourse with the minor;
(b) engages in any sexual act with the minor involving the genitals of one person and the mouth or anus of another person, regardless of the sex of either participant; or
(c) causes the penetration, however slight, of the genital or anal opening of the minor by any foreign object, substance, instrument, or device, including a part of the human body, with the intent to cause substantial emotional or bodily pain to any person or with the intent to arouse or gratify the sexual desire of any person, regardless of the sex of any participant.
(3) A violation of Subsection (2) is a third degree felony unless the defendant establishes by a preponderance of the evidence the mitigating factor that the defendant is less than four years older than the minor at the time the sexual activity occurred, in which case it is a class B misdemeanor.
76-5-401.2. Unlawful sexual conduct with a 16 or 17 year old.
(1) For purposes of this section "minor" means a person who is 16 years of age or older, but younger than 18 years of age, at the time the sexual conduct described in this section occurred.
(2) A person commits unlawful sexual conduct with a minor if, under circumstances not amounting to rape, in violation of Section 76-5-402, object rape, in violation of Section 76-5-402.2, forcible sodomy, in violation of Section 76-5-403, or aggravated sexual assault, in violation of Section 76-5-405, the actor who is ten or more years older than the minor at the time of the sexual conduct:
(a) has sexual intercourse with the minor;
(b) engages in any sexual act with the minor involving the genitals of one person and the mouth or anus of another person, regardless of the sex of either participant; or
(c) causes the penetration, however slight, of the genital or anal opening of the minor by any foreign object, substance, instrument, or device, including a part of the human body, with the intent to cause substantial emotional or bodily pain to any person or with the intent to arouse or gratify the sexual desire of any person, regardless of the sex of any participant.
(3) A violation of Subsection (2) is a third degree felony.
76-5-406. Sexual offenses against the victim without consent of victim -- Circumstances.
An act of sexual intercourse, rape, attempted rape, rape of a child, attempted rape of a child, object rape, attempted object rape, object rape of a child, attempted object rape of a child, sodomy, attempted sodomy, forcible sodomy, attempted forcible sodomy, sodomy upon a child, attempted sodomy upon a child, forcible sexual abuse, attempted forcible sexual abuse, sexual abuse of a child, attempted sexual abuse of a child, aggravated sexual abuse of a child, attempted aggravated sexual abuse of a child, or simple sexual abuse is without consent of the victim under any of the following circumstances:
(9) the victim is younger than 14 years of age;
(10) the victim is younger than 18 years of age and at the time of the offense the actor was the victim's parent, stepparent, adoptive parent, or legal guardian or occupied a position of special trust in relation to the victim as defined in Subsection 76-5-404.1(3)(h);
(11) the victim is 14 years of age or older, but younger than 18 years of age, and the actor is more than three years older than the victim and entices or coerces the victim to submit or participate, under circumstances not amounting to the force or threat required under Subsection (2) or (4); or (12) the actor is a health professional or religious counselor
76-5-402.1. Rape of a child.
(1) A person commits rape of a child when the person has sexual intercourse with a child who is under the age of 14.
(2) Rape of a child is a first degree felony punishable by imprisonment for an indeterminate term of not less than 6, 10, or 15 years and which may be for life. Imprisonment is mandatory in accordance with Section 76-3-406.