A rape shield law limits the introduction of evidence by a defendant charged with rape. The evidence not allowed in concerns the victim’s past sexual conduct. For example, defendants typically can't introduce evidence of the victims' prior consensual sexual relationships. Most states and the federal government have such laws.
Up until the 1970s, under the common law in the United States, evidence of a rape victim's past sexual conduct was broadly admissible and accepted in every rape case. It was believed that if a rape victim consented to sex in the past, she was more likely to have consented to the sexual acts that she claimed amounted to rape. This evidence was also admitted under the theory that a woman's past sexual history could be important in assessing her credibility as a witness. The common-law rules discouraged women from bringing rape charges for fear they would be embarrassed and humiliated at trial.
Great strides were made to reform such rules in the 1970s. These efforts were very successful, and within little over a decade every jurisdiction in the United States had reformed its laws to prohibit using a woman's past sexual history in rape cases. Special evidentiary rules were enacted on the state and federal level to protect the privacy of the victim, and to encourage rape victims to report offenses and to participate in the prosecution of offenses.
Typical rape shield laws provide that in a prosecution for rape, attempted rape, or conspiracy to commit rape, reputation or opinion evidence of the alleged victim's prior sexual conduct is not admissible. Evidence of specific instances of the victim's prior sexual conduct is also inadmissible except in the following circumstances:
(1) the evidence regards the sexual conduct between the victim and the defendant and is introduced to show consent;
(2) the evidence is introduced to prove an alternate source or origin of semen, disease, or pregnancy;
(3) the evidence regards the immediate surrounding circumstances of the alleged crime;
(4) the evidence of previously chaste character is necessary to the successful prosecution of the particular criminal charge.
The procedure involved in introducing evidence covered by rape shield laws is also fairly typical. Generally the defendant must make a motion supported by an offer of proof in which the defendant details what evidence he wishes to introduce and why. The court will generally require that a hearing be held out of the presence of the jury to review the motion and hear arguments in support of and against the motion. If the court finds some of the evidence admissible pursuant to one of the exceptions under the applicable laws, an order must be issued stating the scope of the evidence that may be admitted.
Rape shield laws have expanded to include other evidence that legislatures deem prejudicial, such as clothing of the victim that the defendant tries to introduce to show that the victim consented to or asked for the sexual contact. Those state statutes that do restrict the admissibility of clothing, however, make exceptions where it is introduced to show a struggle (or lack thereof) or proof of the presence (or absence) of bodily fluid such as semen or blood. Rape shield laws have also been expanded in most states to protect victims of all different sexual offenses, regardless of the victim's age or sex.
Defendants have challenged the constitutionality of rape shield laws on many occasions, generally arguing that the laws violate their right to DUE PROCESS and their right to confront their accuser. However, the constitutionality of these laws has consistently been upheld. Specifically, courts have held that the state's interest in protecting sexual assault victims from harassment and humiliation at trial, as well as the highly prejudicial effect such evidence may have on a jury, outweighs the rights of the defendant that may be implicated.
