The review of a trial court's decision by a higher court - what can be appealed and when (the final-judgment rule and its exceptions), the notice of appeal and why missing it is fatal, what "standard of review" means and why most appeals are lost on it, preserving error at trial, the record and briefs, and what an appellate court can and cannot do with the result.
An appeal is not a new trial. It is a review of the trial court's decision, on the record made below, by a panel of judges who read the briefs, may hear a short oral argument, and decide whether the trial court made a legal error serious enough to change the outcome. No new evidence is taken and no witnesses testify. In most systems the losing party has a right to one appeal from a final judgment - the order that ends the case as to all claims and all parties - and any further review, by a state supreme court or the United States Supreme Court, is discretionary and rarely granted. Rulings made during a case generally cannot be appealed until the end; the exceptions include orders granting or refusing injunctions, certain orders certified by the trial judge as involving a controlling question of law, class-certification rulings, and a small class of "collateral" orders that would be effectively unreviewable later.
The appeal is started by filing a notice of appeal within a period the rules fix from entry of judgment, and that deadline is jurisdictional: a notice filed a day late ends the appeal, and no showing of merit revives it, though a timely post-judgment motion (for a new trial, or to alter the judgment) postpones the start of the period. Filing an appeal does not automatically stop the winner from enforcing a money judgment; the appellant must post a supersedeas bond or obtain a stay. The appellant then orders the transcript, the record is assembled, and the parties file briefs on a schedule; the appellee may cross-appeal from any part of the judgment it wants changed. Only errors that were raised in the trial court - by objection, motion or request for a ruling - are ordinarily reviewable; an issue raised for the first time on appeal is forfeited unless it amounts to plain error, which is why lawyers "make a record" during trial even when the objection will be overruled.
The single most important idea in appellate practice is the standard of review, which fixes how much deference the appellate court gives the ruling below. Questions of law - the meaning of a statute or contract, whether the right legal rule was applied - are reviewed de novo, with no deference. Findings of fact by a judge are reversed only if clearly erroneous, and a jury's verdict only if no reasonable jury could have reached it. Discretionary rulings - evidence, scheduling, sanctions, most case-management decisions - are reversed only for an abuse of discretion. Even an established error is not enough: the appellant must show it was prejudicial rather than harmless. The court may affirm, reverse, vacate, or modify, and may remand for further proceedings under its instructions; it may affirm on a ground the trial court never reached. Costs follow the result, and a frivolous appeal can be sanctioned. The whole process usually takes many months, and the losing party may seek rehearing by the panel or by the full court before turning to discretionary review.
The first thing to do after an adverse judgment is to calendar the notice-of-appeal deadline, because everything else can be repaired and that cannot; the second is to ask whether the case is genuinely appealable and on what standard, since an appeal from a discretionary ruling or a jury's view of the facts is usually a poor investment. Appellate work is a distinct skill and many trial lawyers refer it out. A winning party facing an appeal should make sure a bond or stay is in place before any enforcement, and should consider a cross-appeal deadline of its own. Self-represented appellants are held to the same rules on timing, record and briefing as lawyers, and most losses in that category are procedural.
Choose your state. Each link opens the directory page for the city in that state with the most currently published law firms in this practice area; a +n beside the city is how many other cities in the state also have one. The list is generated when this page loads, so a state whose listings have lapsed drops out rather than becoming a dead link.