Concurrent versus consecutive sentences
On occasion, an offender receives multiple sentences for multiple crimes. The judge can order the sentences to be served concurrently or consecutively. Sometimes judges give concurrent sentences, allowing defendants who have been convicted of two or more crimes to serve the sentences simultaneously. At other times, judges impose consecutive sentences, which means that the defendants serve the sentences one after the other.
An appeal is a claim that one or more errors of law or procedure were made during the investigation, arrest, or trial. Appeals usually assert that a judge made an error in admitting evidence that was gathered in violation of the accused's rights or made errors in courtroom rulings. Appeals are based on questions of law or procedure, not on questions of the defendant's guilt or innocence. Neither the federal government nor the states can appeal an acquittal (a verdict of not guilty).
An appellate court can affirm (uphold) the decision of the lower court or it can reverse (overturn) the lower court's decision. Of those who appeal, 20 percent have their convictions overturned. If an appellate court discovers a harmless error (an unimportant or insignificant denial of a constitutional right), it still affirms. But if an appellate court finds a serious error that affects substantial constitutional rights, it reverses. Instead of setting the defendant free, the appellate court sends the case back to the trial court for a new trial. The prosecutor then decides whether to retry the case. If the prosecutor reinstates criminal charges, there is no double jeopardy problem because the reversal makes the first trial moot (for legal purposes, the first trial never happened). Often the defendant is tried for a second time, but not always. On occasion, the appellate court will allow a retrial only with key prosecutorial evidence excluded from the second trial because the appellate court deems it inadmissible.