Well, I'm not so sure. DNA fingerprinting has soared in popularity for criminal cases over the last decade or so. From the figures I vaguely recall being quoted, such evidence of a DNA match narrows down a list of suspects to a mere few hundred thousand people, and is commonly admitted into evidence. This situation is reminiscent of that phenomenon, IMHO.
I imagine that the looser standard of evidence in civil cases would make such information quite significant in determining "the preponderance of evidence".
It would be interesting to hear from some folks with legal training on this issue, if only to correct my mistakes. IANAL.
Well, I missed the beginning of this, but here's the general principle. Any evidence is admissible which makes it more likely that whatever you're trying to prove is true rather than untrue. For example, I want to prove that you stole my watch. I can prove that the thief is a man: since you are a man, this makes it more likely than before that you are the thief. It doesn't prove that you did it, but it goes in that direction -- it narrows it down. Okay? Now, here's the important corollary. If the jury is likely to give undue weight to the evidence, it can be inadmissible even though it would be admissible under the general principle. Lie detector tests are a good example of this, at least in Canada: they're not admissible, and the reason they're not admissible isn't because they don't prove with 100 % certainty, but because the jury is likely to think they're much more reliable than they actually are. Since I have no idea what the original topic was, I leave it to you to apply these general rules to your specific concern as an exercise. :-) Disclaimer: Since I'm in Canada, obviously I can't give any advice regarding US law. Regards, -- Yves Bellefeuille, Ottawa, Canada an448@freenet.carleton.ca (finger here for PGP key) ua294@fim.uni-erlangen.de