what if this came up in a criminal case?

[lizzymahoney]

If this came up in a criminal case the case would be dismissed. DNA could not prove within reasonable doubt, and the rights of the accused demand sufficient proof.

[xoxoxoBruce]

"the rights of the accused" are routinely trampled in paternity cases, lizzymahoney. Especially when the judge says, "I don't care if she is lying, this child needs financial support and you will provide it.

[lizzymahoney]

Just so! Although this article is not about trampling rights in a paternity case.

The topic question, however, is regarding a criminal case, and how this problem would be treated in that venue. My comments addressed that.

Criminal vs family court: two very different standards apply.

[xoxoxoBruce]

That case could very well become a case of trampled rights.

To address your question of DNA failing to prove or disprove a case, we'd have to fall back on what we've been doing for the last few hundred thousand years.
Seakdivers husband, who is the CSI, the guy that wrote the book and teaches it to future Sherlock Holmes in college, can tell you DNA testing is not fool proof and requires a lot of interpretation. It's just one of the tools.