Blood Pattern Evidence Is Admissible, but Is It Really Reliable?

You’ve seen it on TV and in the movies. The police and investigators are at the scene of a bloody murder. The blood appears to have been spattered on walls and the floor. The prosecution uses the blood stains to recreate the murder to establish how the victim was killed. This type of evidence may be fact or fiction, and it can be used in Kentucky courts.

Bloodstain pattern analysis started when a group of scientists and forensic investigators began testifying as experts in criminal cases. They went on to train hundreds of police officers, investigators and crime-lab technicians, and, over time, they testified at trials as well.

If a defendant was found guilty and appealed, arguing that the experts’ testimony wasn’t based on science, but the defendant lost the appeal, the court would set a precedent allowing use of such evidence. That opened the door to its being used in other courts in the same state and other states’ adopting testimony by those doing blood pattern analysis.

Normally non-scientifically-trained judges would rely on the opinions of these supposed experts and approve their use. Rarely, if ever, have courts required objective proof of the accuracy of bloodstain pattern analysis,  according to an article by ProPublica. They chart how decisions over the years paved the way for its use, for better or worse.

In 1957 in the case of People v. Carter, the California Supreme Court ruled bloodstain pattern analysis is a proper area for expert testimony. Paul Leland Kirk testified for the police that, based on his analysis, the murderer was two-and-a-half feet from the victim. He said to the jury that he learned about this analysis by experimentation,  including beating a device made of wood, sponge rubber and a sheet of plastic to learn how different sizes and shapes of blood spots were created. California Supreme Court Justice Jesse W. Carter dissented in part from the majority decision, stating, “It most certainly cannot be said that an object made of wood, sponge rubber and a plastic sheet constituted the same thing as a human head.”

After that decision, state after state agreed. In 1984 an appellate court in Illinois ruled that a police officer with only three weeks of training would qualify as an expert and testify in criminal cases. The next year the Supreme Court of Mississippi held that even if a judge made a mistake in admitting testimony of a supposed bloodstain pattern analyst (he attended a week-long training twelve years earlier), the testimony wasn’t influential enough to merit a retrial.

The Supreme Court of Indiana upheld a conviction in 1987 despite the use of an “expert” by the prosecution, a detective who attended one course on bloodstain pattern analysis seven years earlier who had never testified about such evidence before.

In 1990 the Supreme Court of Minnesota ruled that to be allowed to testify as an expert in bloodstain pattern analysis the person need not have any training in bloodstain pattern analysis, just a background in serology (the study of blood serum).

If a case gets to a trial, expert testimony can be crucial in the outcome, as can the impeachment of the prosecution’s expert testimony when it’s not grounded in the facts or science. If you or a family member is facing criminal charges, you need a criminal defense attorney who can protect your rights and your future. Contact us today so you can discuss your situation with one of the attorneys at the Lexington, Kentucky-based Carman Law Firm. As criminal defense attorneys with years of experience, we offer thorough, experienced representation.