The Ninth Circuit has determined that a beneficiary of a second-preference family-based petition (child of a lawful permanent resident) whose age is calculated to be under the age of 21 by the Child Status Protection Act on the date of his father's naturalization remains under age 21 for visa purposes, and thus, becomes eligible for adjustment of status as an immediate relative. "We conclude that anyone who under the relevant statutes is considered a minor child of an LPR on the date of the parent’s naturalization (and who is the beneficiary of a valid petition for an immigrant visa based on that status) can obtain a visa as the minor child of a citizen following his parent’s naturalization."
The full text of Rodriguez Tovar v. Sessions can be found here:
http://cdn.ca9.uscourts.gov/datastore/opinions/2018/02/14/14-73376.pdf