Source Code On Trial In DNA Matching Case (post-gazette.com)

An anonymous reader writes: While computer analysis by other programs was inconclusive in matching DNA evidence to a suspect, one program, TrueAllele, gave a match. As reported in the Pittsburgh Post-Gazette, an expert witness for the defense wants access to the 170,000 lines of source code to determine whether the match is scientifically valid. Not surprisingly, the software creator is resisting. From the article: "TrueAllele, created by Dr. Perlin and in its current version since 2009, is the only computer software system of its kind that interprets DNA evidence using a statistical model. It can single out individuals in a complex DNA mixture by determining how much more probable a match is versus mere coincidence. Complex mixtures can involve multiple people, as well as degraded or small DNA samples. ... Although the technology is patented, the source code itself is not disclosed by any patent and cannot be derived from any publicly disclosed source. The source code has never been revealed, he said, and it would cause irreparable harm to the company if it were. In his declaration, Dr. Perlin said that reading the source code is unnecessary to validate the program, and that a review could be done in his office or online."

Comments

Re:Wrong industry?

[Layzej]

For instance, for any mission critical component NASA may have three different programs, each written in a different language and running on a unique platform. If at any time one of the programs gives an answer that is not consistent with the other two then the minority report is discarded and the other two are presumed to be correct. No need to halt the proceedings and debug at that point.

In this case there is only one program that finds a match. It should be considered unreliable and discarded.

Speaking as an IT expert witness of 16 years...

[bfwebster]

...I think the defense has the better argument. I have used software tools (both third party and ones I have developed personally) to do source code comparisons and analysis, but they only serve to point me to likely areas of investigation; I have never directly reported and relied upon the output from one of my custom tools in my expert reports.

A key aspect of expert testimony is that your analysis should, in theory, be repeatable by any other qualified expert using the same methodology (which needs to be spelled out in your report). If Perlin is relying directly upon his custom program for his conclusions, he needs to thoroughly expose his methodology -- which, in effect, means either allowing his source code to be reviewed or producing a detailed summary of his methodology that would allow someone else to reproduce it. Trying to claim trade secret status (which is what he's doing, in effect) for a expert methodology is an oxymoron.