Federal courts decide only actual cases and controversies, which generates three threshold doctrines.
Standing. Injury in fact that is concrete and particularised and actual or imminent; fairly traceable to the challenged conduct; and likely to be redressed by a favourable decision. Each element must be supported with the degree of evidence required at each stage — pleading, summary judgment, trial.
Organisational standing. An organisation may sue for its own injuries, or on behalf of members where a member would have standing, the interests are germane to its purpose, and neither the claim nor the relief requires individual participation.
Ripeness. Fitness of the issues for decision and hardship to the parties from withholding review. Pre-enforcement challenges require a credible threat.
Mootness. A live controversy must persist throughout. Exceptions cover disputes capable of repetition yet evading review, voluntary cessation where the defendant is free to resume, and, in class actions, certain claims that survive the named plaintiff’s.
Prudential doctrines including the general rule against asserting the rights of third parties, with exceptions where the rightholder faces obstacles.
Practical consequence. These issues are raised at every stage and may be raised by the court on its own. Pleading them carefully at the outset is substantially cheaper than losing on them after discovery.