If I buy a knife at the local shop then I don't explicitly consent to sharing purchase data with law enforcement either. But I don't think it's especially controversial that law enforcement nonetheless obtains this data with the appropriate warrant and such in the process of solving a crime.

One of the issues in this case is that police did not have a warrant at the time they obtained the baby's DNA sample. They were unable to get one because they did not have probable cause that any individual had committed the crime. And certainly the baby could not have committed the crime, which occurred before it was born.

It was only after the state lab gave them the baby's DNA sample that they were able to establish probable cause and get a warrant for the father.

Perhaps but, "informed consent" within the medical industry is a lot different than at a knife shop.

The nurse probably handed them a form written by the state that outlined all of this. California puts this in 4 easy to read pages which includes mention of law enforcement uses:

https://www.cdph.ca.gov/Programs/CFH/DGDS/CDPH%20Document%20...

And it emphasizes confidentiality and says it's hard and rare for law enforcement to get access to this information. People are going to imagine it only applies in cases like their child being kidnapped or murdered.

Per the article, state polices on sample retention and access are wildly inconsistent. I really don't think a form that outlines a complex topic handed to people right after they've had a baby delivered is adequate notice that cops might treat it as evidence years or even decades later.

I think it does given the golden state killer story made global headlines. That being said it is still rare that this data are used, and the document covers that you can always destroy your samples.