What is Forensic Toxicology?
Forensic toxicology involves detected what substances were present in a person. It’s commonly used in the legal system, especially for suspects of crimes and victims. While the field is often used to detect drug and alcohol use, it can detect a wide array of illicit and legal substances as well.
Whether a victim or suspect has used drugs while a crime was committed can help detectives determine if anyone involved was inebriated. This is common in cases where a person is suspected of driving under the influence of alcohol or narcotics. In fatal car incidents, law enforcement agencies typically take blood samples to find out if any involved drivers were inebriated. People on probation often have to take drug tests as well, and failing a test can lead to a violation of probation, potentially resulting in jail time or other penalties.
Testing for Inebriation During a Crime
There are a variety of techniques for testing whether a person was inebriated, but interpreting results can be complex. Blood-alcohol levels are fairly simple to measure, and even a simple test using the person’s breath can give a reliable reading; blood tests tend to be even more accurate. Various drugs, including marijuana, cocaine and heroin, leave behind markers after use, but some drugs clear out of the system before others. While it’s difficult to determine when people used a substance and if it affected their state of mind during a crime, this evidence often makes its way into courtrooms.
Detectives often piece together stories to determine if all parties are being truthful, and forensic toxicology can be a useful tool. Determining the time frame of a crime can be crucial for piecing together a narrative. For example, forensic toxicology might involve checking for undigested and partially digested foods to determine what the victim ate and when they ate it. Combined with other factors, this information can help detectives check on alibis. These techniques can be especially useful when dealing with decomposing bodies that can’t be investigated with more traditional methods.
While blood screening is the most popular means of checking for substances, human hair can bear signs of substance use as well. Human hair grows at a fairly predictable rate, and substance abuse from many months ago can sometimes be detected. Stomach fluids can also reveal pills and other drugs even if the food is fully digested. Urine sampling provides an easy way to test for drugs without having to draw blood.
Forensic Toxicology in the Courtroom
The field of forensic toxicology plays a major role in many cases, but not all evidence is admissible in typical courtrooms. While blood and urine samples are generally viewed as reliable, hair sampling is a newer field lacking the rigor of other types of tests. Judges might refuse to allow certain tests if they haven’t been proven reliable. Even if evidence can’t be admitted in court, it can help generate leads for further investigation, and prosecutors can typically use this evidence when presenting a case.
Defending Against Toxicology Results
There have been a number of high-profile cases where toxicology results have been proven unreliable. Contamination within a lab can lead to false positives, and defense attorneys can often cast doubt on certain tests or even have then disallowed in court. There have also been a number of cases where forensic scientists have falsified results. Because toxicologists work so closely with prosecutors, some experts have made a case that results should be suspect if the sample is not appropriately blinded. These issues also commonly arise during appeals, and even people convicted can sometimes receive a new trial if the evidence is flawed.
Forensic toxicology is a powerful tool for detectives, and the field continues to grow. However, the fast growth of the field means interpreting results can be difficult as mistakes and flaws in methodology can cast doubt on tests that seem compelling to a jury. When defending a case, lawyers will examine the forensic data to find out if there are flaws that can lead to an acquittal. Because these tests are often the cornerstone of a case, dismissing this evidence can be powerful.