What is the test for a motion to reduce a defendant's sentence under section 3582(c)(2) of the Criminal Code?

Where a defendant is permitted to seek a reduction, the district judge may conclude that a reduction would be inappropriate. Freeman v. United States, 131 S.Ct. 2685, 2694 (2011). A court may take into account a defendant's decision to enter into a plea agreement and if it "concludes the agreement led to a more lenient sentence than would otherwise have been imposed, it can deny the motion, for the statute permits but does not require the court to reduce a sentence. This discretion ensures that 3582(c)(2) does not produce a windfall." Id.