P.R. Laws Ap. tit. 32A, § IV, Rule 21
In any prosecution for rape or attempt to commit rape, evidence of the victim’s past sexual conduct or history or opinion or reputation, evidence regarding such sexual conduct or history is not admissible for the purpose of attacking her credibility or establishing her consent, unless circumstances of a special nature show that such evidence is relevant and that its probative value outweighs its defamatory or prejudicial character.
If the defendant seeks to offer under such special circumstances evidence of the victim’s sexual conduct or history, or evidence of opinion or reputation regarding such sexual conduct or history, he shall follow the following procedure:
(a) The defendant shall file before the court and the prosecuting attorney a written motion sworn by him specifying the evidence he seeks to offer and stating its relevancy in attacking the victim’s credibility or establishing her consent.
(b) If the court determines that such evidence is sufficient, it shall order a hearing in chambers out of the presence of the jury. In this hearing, the victim may be questioned on the evidence proposed by the defendant.
(c) If the court, at the conclusion of the hearing, determines that the evidence which the defendant seeks to offer is relevant, and that the probative value of such evidence outweighs its defamatory or prejudicial character, it shall make an order specifying what evidence may be offered by the defendant, and the nature of the questions to be permitted. The defendant may then offer evidence pursuant to the order of the court.