[1] Greenlaw had been charged in federal district court in Minnesota with eight counts related to his participation in gang-related sales of crack cocaine in a neighborhood on the south side of Minneapolis.

"In our adversary system, in both civil and criminal cases, in the first instance and on appeal, we follow the principle of party presentation.

The Eighth Circuit, nevertheless, predicated increasing Greenlaw's sentence by 15 years on its reading of the plain-error rule of Fed.

"A plain error that affects substantial rights may be considered [on appeal] even though it was not brought to the [lower] court's attention."

In the absence of a cross-appeal, the plain-error rule does not allow appellate judges to interfere with the assessment of high-level executive-branch officials who may have decided that appealing a sentence in a particular criminal case was not a wise expenditure of resources.

Reading § 3742 to allow appellate courts to sua sponte increase criminal sentences without an appeal from the government would "give with one hand what it takes away with the other."

Executive-branch officials would be vested with the discretion to seek an increased sentence, but their decision not to do so could be overridden by judicial officers; Congress, in enacting § 3742, would not have intended such an inconsistent result.