The Ninth Circuit has rejected the derivative citizenship claim of a lawful permanent resident whose father naturalized before his 18th birthday. In doing so, the court noted that even assuming the petitioner’s parents entered into a de facto union in Peru (roughly the equivalent of a common law marriage), there was no proof of a legal separation between his parents. “Nothing about the Peruvian court’s determination that Hernandez had abandoned the family and lost her parental rights says anything about the type of relationship that existed between her and Walter, much less that it had been formally terminated.”
The full text of Giha v. Garland can be found here:
https://cdn.ca9.uscourts.gov/datastore/opinions/2021/09/02/15-73085.pdf