Appeal

In general. Appellate review, based as it is upon the written record assembled at the trial level, is often deferential, particularly with regard to discretionary trial management decisions, issues heavily intertwined with fact and testimonial credibility, and the trier of fact's determination of guilt. Review of the trial court's elaboration of legal standards is generally de novo, and many jurisdictions also review de novo the application of constitutional or other legal standards to the facts (e.g., Ornelas v. United States, 517 U.S. 690, 699 (1996)).

Conviction by guilty plea. Appeals from a conviction by guilty plea are typically limited to claims that the trial court lacked jurisdiction, that the procedure for entry of the plea was defective, that the sentence was illegal, and, in some states, that the charge failed to state an offense. Other objections are generally deemed to have been waived by entry of the plea. While convictions by plea far outnumber convictions after trial, appeals from conviction at trial far outnumber appeals from conviction by pleas (Davies, p. 558).

The federal government (see Fed. R. Crim. Proc. 11(a)(2)) and nearly half the states permit a defendant (typically only with government consent and court approval) to enter a conditional guilty plea, which reserves the right to appeal on a specified issue. If the appeal prevails, the defendant is then permitted to withdraw the earlier plea and to plead anew.

Review of sentence. In the United States, unlike many other countries, appellate review of a sentence imposed under traditional indeterminate systems rarely extended beyond ensuring that the sentence did not exceed the statutorily authorized punishment or was not influenced by factors that could not constitutionally be considered (e.g., Dorszynski v. United States, 418 U.S. 424, 431–32 (1974)). Appellate review of sentences has become far more common and somewhat more robust, however, in the last quarter of the twentieth century, for several reasons: (1) a number of states have extended review of sentencing decisions to embrace claims of clear abuse or clear mistake; (2) a significant minority of states have adopted determinate sentencing systems, which typically authorize appeals contending that the sentence violated applicable rules; and (3) review of death sentences is now routine to ensure compliance with the complex state and federal rules governing capital punishment.

Prosecution appeals of sentences have most commonly been authorized in determinate sentencing systems (e.g., 18 U.S.C. § 3742(b)), and in general do not violate the double jeopardy clause. However, the prosecution may not appeal the sentencer's refusal to impose a death sentence—a decision ordinarily treated as an "acquittal" of capital punishment (Bullington v. Missouri, 451 U.S. 430, 446 (1981)).

Issues not properly raised. Every jurisdiction prescribes rules of pretrial and trial practice governing when and in what fashion particular objections (e.g., to the adequacy of the charge, to the admission of evidence, or to jury instructions) must be made. To induce compliance with those rules and promote orderly judicial administration, appellate courts ordinarily will not consider objections that were not properly presented at the trial level and consequently not ruled upon by the trial court.

Limited exceptions to this rule are typically recognized. First, a procedural requirement that itself violates due process cannot bar appellate review (Reece v. Georgia, 350 U.S. 85 (1955)). In addition, most states permit a defendant to challenge the trial court's jurisdiction for the first time on appeal; states divide more evenly on whether they permit appeal of issues not raised below but based on newly announced legal decisions.

The most important and virtually universal exception authorizes appellate courts to consider "plain error," whether or not properly raised below. To qualify as plain error under the federal doctrine, an error must not only be clear and obvious, but must also be shown by the defendant to be prejudicial, in the sense of likely affecting the outcome of the case (United States v. Olano, 507 US. 725 (1993)). In determining whether to reach an issue raised for the first time on appeal, many states will consider, in addition to factors similar to those that govern under federal law, whether the legal issue is of general significance, whether it is constitutional in nature, and whether its consideration would promote judicial economy or the public interest.

In the end, plain error has proven hard to define and has a somewhat discretionary character. In practice, it is more likely to be found when defense counsel's representation was questionable or when the evidence of guilt is relatively weak.