ANNAPOLIS – In a 6-1 ruling, the Maryland Court of Appeals Wednesday upheld the admissibility of DNA evidence and the statistical measures used in the science of matching criminals with crime scenes.
The decision, written by Judge Irma S. Raker, affirms the December 1992 circuit court conviction of Michael Devon Armstead in a Howard County rape and burglary trial. Armstead is serving two consecutive life terms plus twenty years in the Maryland Penitentiary in Baltimore.
Armstead was convicted on 10 charges, including assault, burglary, and first-degree rape in connection with a home break- in Jan. 29, 1991.
The victim provided a description matching Armstead’s appearance and clothing on the night of the crime, and identified his photograph. A neighbor identified Armstead as the person seen fleeing the home. Police found items used in the attack in the area where Armstead was apprehended, and Armstead was given a blood test for a DNA comparison with semen recovered from the victim.
Armstead’s attorney sought to overturn the conviction, arguing that admission of DNA evidence at the trial violated the intent of a state statute and Armstead’s constitutional due process rights. In opposition, the State of Maryland argued that despite a small chance of error in DNA testing, the circuit court judge had acted appropriately.
At issue was a descriptive mathematical technique used to determine the probability of a match between a person’s DNA and the DNA in bodily substances found at a crime scene. That technique, called the “product rule,” is “no longer generally accepted in the scientific community,” Armstead’s appellate brief said.
The brief also argued that, under state law, DNA analysis methods require review in a pre-trial hearing.
In place of the product rule, Armstead’s lawyer argued that a newer statistical method called the “ceiling principle” should have been applied. The ceiling principle takes into account certain demographic probabilities for possessing certain genes.
Scientific experts at Armstead’s trial informed the court that the product rule indicated a one in 480 million chance that Armstead’s DNA was a match, compared to a one in 800 million chance under the ceiling principle.
But Gary Bair, chief of the Attorney General’s Criminal Appeals Division, said the 1990 Maryland statute governing use of DNA evidence “was passed with the background that… the DNA testing was scientifically reliable.”
Bair added that the law was written specifically to eliminate the need for extensive expert testimony on the reliability of DNA tests in every criminal case.
The Court of Appeals agreed. “The General Assembly’s choice of language alone…strongly suggests that the Legislature intended DNA profile evidence to be admitted without re- evaluation of the technique’s general reliability,” the decision said.
The court also noted that “the alleged technical defects related to the DNA testing were fully explained to [Armstead’s] jury by the experts.” And it rejected Armstead’s concern that the DNA tests experienced a laboratory error rate of 0.7 percent, noting that the jury was instructed to take that fallibility into account.
The ruling affirmed the Court of Special Appeals decision in the case.
Judge Robert M. Bell was the lone dissenter. While accepting some of the majority’s decision, Bell said the lower court should have evaluated the accuracy and reliability of the laboratory procedures before admitting DNA evidence in the trial.
State law, Bell wrote, “does not divest trial courts of their discretion… to exclude DNA profile evidence if its… value is outweighed by its prejudicial impact.” Bell said that Armstead should have been “entitled to a hearing to consider the admissibility of the DNA profile evidence, followed by a new trial.” -30-