Toxicology testing is used to detect the presence of drugs and toxins in an individual's body through biological matrices such as blood, urine, and hair. In addition, forensic toxicologists can provide interpretations of the concentration of drugs and toxins in a person's system. Toxicological evidence provides useful information that can establish whether or not the victim of a sexual assault was incapacitated or significantly impaired by a drug or toxin. In cases of alcohol and drug-facilitated sexual assault (DFSA), victims are physically and mentally incapacitated to impair a victim's decision regarding consent in sexual assault. The Bureau of Justice Statistics (BJS) estimates that 39 percent of sexual assaults in the United States from 2005-2010 were linked to a victim being under the influence of alcohol or drugs at the time of the incident. Forensic toxicology can have a significant role in determining the contribution of drugs in sexual assault cases. It assists in establishing drug/toxicant concentration thresholds capable of impairing capacity to consent to sexual acts. It also helps in corroborating or disproving various versions of what happened in allegations of sexual assault. Although comprehensive toxicology screens are not recommended as standard protocol for alleged victims in sexual assault cases, they are used when a DFSA is suspected. Procedures outlined for toxicology screens encompass specimen collection, sample preparation, drug screening, drug confirmation, and data review and presentation. Limitations of toxicological evidence are noted.