US v. May: May entered a guilty plea to drug and gun charges via a Rule 11(c)(1)(C) plea bargain with the Government. The agreement called for a sentence of 240 months total in prison (180 months on the drugs, consecutive 60 on the gun). The probation officer calculated the applicable Guideline range as 151 to 188 months (plus the consecutive 60 months for the gun). The district court accepted the plea and imposed the 240-month sentence. Years later, the district court sua sponte denied May a sentence reduction under 18 USC 3582(c)(2) because his sentence was based on the plea agreement, not a Guideline range that had since been changed. May (now with appointed counsel) filed a motion for reconsideration, which the district court also denied.
On appeal, the Fourth Circuit affirmed the denial of the 3582 motion. The court found that May's plea agreement did not specifically tie his sentence to a particular Guideline range that had subsequently been changed by retroactive amendments. As a result, the sentence wasn't based on a Guideline range that had been subsequently lowered and May was not eligible for a reduced sentence.