The Presence of DNA and the Consent Defense in Louisiana Rape and Sexual Assault Cases

DNA evidence routinely arises in Louisiana sexual assault cases, particularly in rape allegations. When consent is raised as a defense, the presence of DNA on the body of the accuser is expected and is consistent with consent. DNA test results do not prove that a rape or sexual assault occurred. Without additional facts, the presence of DNA on an accuser simply proves that the accused’s DNA somehow got on the accuser. Since DNA is easily transferred, it is important to attempt to find out why that DNA is found in a particular location. A DNA examiner cannot testify as to whether consent existed during a sexual encounter nor how that DNA got on a particular location. It’s possible DNA could be located on an accuser’s body without any direct contact between the accuser and accused because of a phenomenon known as secondary transfer of DNA. Only the accuser, the accused, and any other witnesses can possibly testify and provide additional details to help a jury determine whether consent existed and how the accused’s DNA got to a particular location.
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In contrast with a consent case, if an accused denies having ever had a sexual encounter with an accuser, DNA can become a powerful tool for testing the truthfulness of such an assertion. If the accused’s DNA is found, for example, within an internal vaginal swab of the accuser, the accused’s defense may be refuted depending on the specific facts. Even still, a consent defense may not be refuted. For example, if the accused’s genitalia was touched by the accuser, and she engaged in vaginal stimulation, one might expect to find the accused’s DNA inside her even if the accused never physically engaged in penile penetration. If the accuser claimed penile penetration, the presence of DNA in her vagina would not potentially refute the accused’s defense unless the DNA present is coupled with identified semen and sperm indicating ejaculation or, perhaps, the presence of Prostate Specific Antigen (PSA), indicating ejaculation. But what if the accused told investigators that he ejaculated while being manually stimulated by the accuser’s hand; his semen got on her hand; and then she vaginally stimulated herself without wiping her hand? Assume also that the accuser claimed penile penetration. Then, one might still expect to find the accused’s DNA and semen inside the accuser’s vagina even if there was no penile penetration. The presence of DNA and semen would be consistent with both the account of the accuser and the accused in this scenario. As you can see, every case is highly fact-dependent. Under these scenarios, the presence of DNA alone would not prove that a rape or sexual assault occurred. DNA can only potentially be helpful in evaluating the credibility of witnesses in a sexual assault case. Often, far more than DNA is needed to determine who may be telling the truth in such a case. 

Consider also a case in which the accused’s DNA is only found on the clothing of the accuser even though she claims she was vaginally raped. Assume internal and external vaginal swabs were taken. A lack of DNA in this hypothetical from these vaginal swabs could potentially support an accused’s defense that he did not vaginally rape the accuser but rather was engaged in foreplay by rubbing the outside of her clothing with his hands and stopped when the accuser indicated she was uncomfortable with moving forward during a sexual encounter. In this case, one would expect to find DNA on the clothing if the accused is telling the truth or expect to find the presence of DNA on and/or within the accuser’s vagina if she is telling the truth. If only DNA is found on the clothing, it is likely that the accused is telling the truth. Even still, a lack of DNA on the accuser’s vagina would not necessarily refute her account. If the accused wore a condom, for instance, and non-consensually penetrated the accuser, it’s possible no DNA would be found inside her even though she is telling the truth about being penetrated. 

DNA’s discriminatory power is potentially enhanced when an accuser and an accused’s stories contradict one another, such as when one person claims consent and the other does not. On the other hand, when the defense claims consent, and the accuser claims rape or sexual assault, one expects to find the presence of DNA even though both claims are inconsistent. Additional factors, such as the consumption of alcohol or drugs, contradictory accounts, inconsistent behavior, the presence of injuries, etc., must also often be used with DNA forensics when assessing witness credibility in sexual assault cases. These cases often highly depend on witness credibility and are, thus, fact-intensive. To complicate matters, alcohol consumption by both parties is often involved in sexual assault allegations. To ensure you are not wrongfully convicted, it’s important to consult with a knowledgeable and informed Louisiana criminal defense lawyer if you face a Louisiana rape or sexual assault allegation in which DNA forensics are involved.