US v. Mercado-Moreno, No. 15-10545 (8-28-17)(Tallman, Ikuta, & Oliver). This case concerns a district court's quantity findings when deciding a reduction of sentence pursuant to a retroactive Guideline amendment.  In this instance, the 9th found no error in the second district court concluding that the retroactive amendment did not apply as the first court had determined that the amount of meth for which the defendant was responsible did not lower his guidelines.  Concerning findings, the 9th holds "that when deciding a 3582(c)(2) motion, a district court may supplement the original court's quantity findings only when supplemental findings are necessary to determine the defendant's eligibility for sentence reduction in light of the retroactive Guideline." Further, "a district court has broad discretion in how to adjudicate 3582(c)(2) proceedings, including whether to hold a hearing when making supplemental findings of drug quantity." (5)

The decision is here:

http://cdn.ca9.uscourts.gov/datastore/opinions/2017/08/28/15-10545.pdf