Does a federal court appeal involve a new trial?

Rather than a trial, the Court of Appeals decides a federal court appeal on the basis of the "record" in the United States District Court, which refers to the record from the initial trial. It does not consider new evidence, and though the courts schedule oral argument in most cases, circuit courts in some circuits may deny oral argument. Most circuits also require mediation in an effort to settle the appeal. 

What is the role of the federal appeals court?

The role of the federal appeals court is very different from the district trial court. Under federal law, the appeals court decides matters of law, not fact. This is because the appeals court does not have time to hear the witnesses or watch the full case. Instead, the federal appeals judges are given the full, cold record to review along with the briefs provided by the attorneys. With this cold record, they can only fairly rule on matters of law.

The matters of law that the federal appeals court reviews are the various decisions made by the judge overseeing the case. For instance, in the trial court, the judge is constantly hearing and ruling on objections from the attorneys. Sometimes a judge makes the wrong decision with an objection and it materially affects the final conclusion of the case. When this happens, the appeals court will reverse that incorrect matter of law and correct the judgment if warranted. Sometimes the appeals court will order a new trial.

What happens when the court orders a new trial?

When the court orders a new trial, the case is sent back to the same judge for retrying. The judge, and sometimes a fresh jury, hear the entire case over again from beginning to end and make a new decision. In the interest of court efficiency, ordering new trials is reserved only for correcting the most egregious mistakes by trial court judges. In most cases, the federal appeals court is able to simply correct the judgment themselves and move the case through to its conclusion.