An ex parte decision is one decided by a judge without requiring all of the parties to the dispute to be present.U.S. legal doctrines, ex parte means a legal proceeding brought by one party in the absence of and without representation of or notification to the other party. In Commonwealth common law jurisdictions, the title typically appeared as R v (Defendant), ex parte (Claimant); in the US, this was shortened to Ex parte (Claimant). A proceeding in an executive agency to establish a right, such as patent prosecution, can also be ex parte.

Although some courts permit appeals at preliminary stages of litigation, most litigants appeal final orders and judgments from lower courts. A fundamental premise of many legal systems is that appellate courts review questions of law de novo, but appellate courts do not conduct independent fact-finding.Instead, appellate courts will generally defer to the record established by the trial court, unless some error occurred during the fact-finding process.Many jurisdictions provide a statutory or constitutional right for litigants to appeal adverse decisions.However, most jurisdictions also recognize that this right may be waived. In the United States, for example, litigants may waive the right to appeal, as long as the waiver is "considered and intelligent".

he appellate process usually begins when an appellate court grants a party's petition for review or petition for certiorari.Unlike trials, which many common law jurisdictions typically perform with a jury, appeals are generally presented to a judge, or a panel of judges.Before hearing oral argument, parties will generally submit legal briefs in which the parties present their arguments at length in writing.Appellate courts may also grant permission for an amicus curiae to submit a brief in support of a particular party or position.After submitting briefs, parties often have the opportunity to present an oral argument to a judge or panel of judges.During oral arguments, judges often ask questions to attorneys to challenge their arguments or to advance their own legal theories.After deliberating in chambers, appellate courts issue formal written opinions that resolve the legal issues presented for review.

State courts vary in their use of ex parte proceedings for example, in custody cases, replevin cases and other civil matters, though most have it in one form or another. For example, in the States of California and Illinois, ex parte proceedings are available if notice is given before 10 a.m. the previous court day, or even shorter upon showing of emergency need. As most courts in these two states hold law and motion hearings in the early morning, this notice is typically confirmed by facsimile although oral notice may be effective. Some courts in California have procedures to allow opponents to appear telephonically, while other courts do not allow any oral argument and only consider written papers. In California, the party who files an ex parte application must file a declaration showing compliance with these requirements, and no relief may be granted absent such declaration. In addition to the notice requirements, an ex parte application must contain an affirmative actual showing in a declaration based on personal knowledge of "irreparable harm, immediate danger, or any other statutory basis for granting relief ex parte

In the United States, the availability of ex parte orders or decrees from both federal and state courts is sharply limited by the Fifth and Fourteenth Amendments, which provide that a person shall not be deprived of any interest in liberty or property without due process of law. In practice this has been interpreted to require adequate notice of the request for judicial relief and an opportunity to be heard concerning the merits of such relief. A court order issued on the basis of an ex parte proceeding, therefore, will necessarily be temporary and interim in nature, and the person(s) affected by the order must be given an opportunity to contest the appropriateness of the order before it can be made permanent.