In-laws connection insufficient for probable cause

The Tenth Circuit decided Poolaw v. Marcantel, No. 07-2254 (10th Cir. May 4, 2009), a 1983 case, where officers searched a suspect's in-law's property and stopped a suspect's sister-in law mostly because they were the suspects' in-laws. The Court held that familial relationship, by itself, is insufficient for probable cause:

Adhering to established Supreme Court precedent and the unanimous case law of this and other courts, we hold that a familial relationship is insufficiently particularized to justify invading an individual’s reasonable expectation of privacy. Applying this rule to the present case, we conclude that the Poolaws’ status as Astorga’s in-laws, combined with the meager additional facts known to Marcantel and Hix, were insufficient to support a finding of either probable cause to search the property or reasonable suspicion to detain Chara. Further, because these Fourth Amendment principles were clearly established at the time of their actions, Marcantel and Hix are not entitled to qualified immunity.

Might be useful in some other Fourth Amendment contexts.

There's probably some sort of in-laws joke in here, but it's escaping me.

Kudos to David Freund for the tip.