Thu, 30 Sep 1999 13:46:02 -0400

On Thu, 30 Sep 1999 09:35:31 -0400 Matthew Gaylor <> writes:
> by Victor Mil·n <>

What, precisely, prevents prosecutors from
> simply printing out graphics and columns of figures that support
> their contention? If they are trying to "prove" that DNA samples
> taken from a crime scene match sequences from their suspect, what's
> to prevent them simply showing two copies of the same slide, side by
> side? Could you tell the difference? To accomplish it wouldn't even
> entail much of a "conspiracy:" one person along the chain of evidence
> could effect the switch, and it would be hard to trace in the face of
> the automatic/reflex government stonewall.

A defense attorney should be smart enough to object to the state presenting printouts without first hand testimony as to their authenticity. The DNA analysis procedure is not under the control of the prosecution; the job is contracted to an independent lab. Copies of the results are provided to the prosecutor and the defense, and are filed at the lab. At trial, a responsible expert from the lab testifies as to the authenticity of the results. A more likely method of evidence tampering would be misattribution of the samples given to the lab. But that is under standard chain of custody control, which applies to any evidence, not just DNA. And a defense attorney should be smart enough to critique possible problems in the chain of custody.

> Evidence such as DNA matching is functionally "sourceless," since
> even if you were provided complete documentation on it, you still
> couldn't understand it: unless you're already an expert, you have no
> common-sense way to judge whether it's valid or not.
> Allowing the government to introduce evidence without accounting for
> it _at all_ goes light-years beyond the incomprehensibly
> esoteric: it gives the government carte blanche to just frame you.
> They can hang anything on you.

Evidence which requires expert interpretation is nothing new. That's why they have expert witnesses. Laymen may not have the knowledge of the experts, but the credentials of the experts can be presented and argued, and one expert can dispute the testimony of another expert. And in the end, the jury always has the option of acquittal if the expert testimony is unconvincing.

> A government spy could sign up for Hotmail, say, using your name,
> send messages in which "you" describe plans to blow up Tipper Gore or
> give away crack rocks instead of candy on Halloween, and then
> introduce printouts of those messages into court as evidence.

A defense attorney should be smart enough to point out how easy it is to forge email. And 20% or more of the jury pool should be able to understand that, based on their own knowledge of how email works.

> Remember: if this law passes, the government doesn't have to say
> where it comes from or how it got it.

I thought the article said the law exempts the government from revealing cryptanalysis technology. That's not the same thing as saying the government does not have to justify where evidence comes from or how they got it. In other words, if a government expert is called to testify, it sounds like the law would only exempt him from detailing a cryptanalytic method. The government could present the private key at trial, to show that it decrypts the message as alleged, without revealing the mathematical method by which the message was analyzed to recover the key.

If the government is to have some limited legal authority to use cryptanalysis, it is reasonable on the face of it that the law would offer some protection for the government from having to reveal crypto secrets at trial.

Ron Kean





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