Today's Idaho Supreme Court case Idaho v. John & Jane Doe is almost a primer on key parts of the 4th amendment, on search and seizure - notably when the search comes to your own body. It's not long (10 pages, including the legal analysis) and worth the read.
The background: A girl is convicted of petit theft, which puts her in the juvenile corrections system and into contact with the two parents. The Supreme Court summarized what happened next: "Because a social investigation revealed that the Does had a history of drug abuse and that Jane was on probation for possession of marijuana drug paraphernalia, the magistrate questioned the Does about their use of controlled substances. Jane admitted to the magistrate that she used methamphetamine before having her children and had continued to smoke marijuana until she was caught with paraphernalia sometime prior to the events in this case. The magistrate consequently required both John and Jane to undergo random drug urinalyses as a term of their daughter’s probation."
So: Conviction of the daughter on a theft charge leads to de facto body searches of the parents for traces of drugs?
The Idaho Supreme ultimately decided not, though the route to that conclusion is by no means as simple as you might imagine.