Appeals judges generally resist overruling trial court judgments and prefer to give trial judges wide discretion in the conduct of trials. As many appellate courts have said, defendants are not guaranteed "perfect" trials. Normally an appellate court will overturn a guilty verdict only if the trial court made an error of law that significantly contributed to the outcome. Put differently, an error by the trial judge will not lead to a reversal of a conviction as long as the error can reasonably be considered harmless. Not surprisingly, most errors are deemed "harmless," and consequently few convictions are reversed. However, some types of errors are so grievous that they are presumed harmful, such as the use of a coerced confession in violation of the 14th Amendment.
Sentences are a different matter. When the trial judge is given discretion over the sentence, the appellate court will rarely interfere. However, if the law requires a particular sentence and the judge gets it wrong, the appellate court will usually send the case back for resentencing.
In most modern American jurisdictions, a "writ" is an order from a higher court to a lower court or to a government official such as a prison warden. Defendants may seek several types of writs from appellate judges directed at the trial court or at a lower appellate court. (Many states have two levels of appellate courts -- an intermediate appellate court and the state supreme court.)
Writs, like appeals, are complex and involve picky details. Defendants facing situations where they may be entitled to take a writ should consult counsel.
Writs usually are considered to be extraordinary remedies, meaning they are permitted only when the defendant has no other adequate remedy, such as an appeal. In other words, a defendant may take a writ to contest a point that the defendant is not entitled to raise on appeal. As a general rule, this applies to issues that are not apparent in the record of the case itself (such as when an attorney fails to investigate a possible defense).
Any one of the following reasons, for example, may prohibit an appeal (and justify a writ):
Defendants who want to challenge the legality of their imprisonment -- or the conditions in which they are being imprisoned -- may seek help from a court by filing an application for what is known as a "writ of habeas corpus."
A writ of habeas corpus (literally to "produce the body") is a court order to a person (prison warden) or agency (institution) holding someone in custody to deliver the imprisoned individual to the court issuing the order. Many state constitutions provide for writs of habeas corpus, as does the U.S. Constitution, which specifically forbids the government from suspending writ proceedings except in extraordinary times -- such as war.
Known as "the Great Writ," habeas corpus gives citizens the power to get help from courts to keep government and any other institutions that may imprison people in check. In many countries, police and military personnel, for example, may take people and lock them up for months -- even years -- without charging them, and those imprisoned have no avenue, no legal channel, by which to protest or challenge the imprisonment.
The writ of habeas corpus gives jailed suspects the right to ask an appellate judge to set them free or order an end to improper jail conditions, and thereby ensures that people in this country will not be held for long times in prison in violation of their rights. Of course, the right to ask for relief is not the same as the right to get relief; courts are very stingy with their writs.
For clear and complete explanations of all aspects of criminal law and procedure, get The Criminal Law Handbook: Know Your Rights, Survive the System, Paul Bergman and Sara J. Berman (Nolo).
An appeal is a request to a higher (appellate) court for that court to review and change the decision of a lower court. Because post-trial motions requesting trial courts to change their own judgments or order new jury trials are so seldom successful, the defendant who hopes to overturn a guilty verdict must usually appeal. The defendant may challenge the conviction itself or may appeal the trial court's sentencing decision without actually challenging the underlying conviction.