Thomas Robert Kammer v. Christine J. Young
73 Md. App. 565, 535 A.2d 936 (1988)
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Rule of Law:
Blood test evidence in a paternity proceeding that meets statutory thresholds for admissibility, including a statistical probability of paternity calculated using standard methodologies accepted within the scientific community of paternity testers, is admissible, and any challenges to the methodology's scientific precision go to the weight of the evidence, not its admissibility.
Facts:
- Christine J. Young gave birth to a child on May 24, 1982.
- Young alleged that Thomas Robert Kammer was the only man with whom she had sexual intercourse in the year preceding the child's birth.
- Kammer contended that his sexual relations with Young had ceased more than 15 months before the child was born.
- Blood tests of Young, Kammer, and the child were performed by an approved laboratory.
- The tests yielded a "paternity index" indicating it was 460 times more likely that Kammer could produce the required sperm than a random man.
- Using a standard prior probability of 0.5, the lab converted the paternity index into a 99.78% statistical probability of paternity.
- Larry Klouser, a man whom Kammer alleged also had a relationship with Young, died prior to the trial.
- Kammer's sister proffered testimony that Klouser had admitted to a sexual relationship with Young during the conception period and stated he could have been the father.
Procedural Posture:
- Christine J. Young initiated a paternity action against Thomas Robert Kammer in the Circuit Court for Baltimore City, a trial court.
- A jury trial was held, resulting in a verdict that Kammer was the father of Young's child.
- The trial court entered a decree based on the jury's verdict.
- Kammer, as appellant, appealed the decree to the Court of Special Appeals of Maryland, with Young as the appellee.
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Issue:
Does the admission of blood test evidence in a paternity case, which uses a standard 0.5 prior probability in Bayes' Theorem to calculate a statistical probability of paternity, violate either the governing state statute or the alleged father's constitutional due process rights?
Opinions:
Majority - Bishop, Judge
No. The admission of blood test evidence calculated using standard methodologies does not violate the state statute or the alleged father's due process rights. The legislature, in drafting the statute, intended for the term 'statistical probability' to be understood as it is used by the blood testing community, not by pure statisticians. The methodology used, including applying Bayes' Theorem with a 0.5 prior probability, is universally accepted in the relevant scientific community of paternity blood testers. Therefore, once the statutory threshold of 97.3% is met, the evidence is admissible, and any attacks on the scientific formula or witness qualifications go to the weight the jury should give the evidence, not its admissibility. This process does not violate due process because the statistical evidence is not conclusive; the alleged father remains free to present non-genetic evidence to challenge the underlying assumptions and rebut the finding of paternity.
Analysis:
This decision solidifies the legal framework for admitting modern genetic paternity evidence in Maryland, giving significant deference to the established practices of the relevant scientific community. By ruling that challenges to the standard statistical methodology (like the use of a 0.5 prior probability) affect the weight of the evidence rather than its admissibility, the court lowered the barrier for introducing powerful probabilistic evidence. This precedent makes it more difficult for alleged fathers to exclude incriminating blood test results on technical grounds, shifting the legal battle from pre-trial motions to jury persuasion regarding the evidence's credibility and significance.
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