In law, standing or locus standi is the term for the ability of a party to demonstrate to the court sufficient connection to and harm from the law or action challenged to support that party's participation in the case. Standing exists from one of three causes:
- The party is directly subject to an adverse effect by the statute or action in question, and the harm suffered will continue unless the court grants relief in the form of damages or a finding that the law either does not apply to the party or that the law is void or can be nullified. This is called the "something to lose" doctrine, in which the party has standing because they directly will be harmed by the conditions for which they are asking the court for relief.
- The party is not directly harmed by the conditions by which they are petitioning the court for relief but asks for it because the harm involved has some reasonable relation to their situation, and the continued existence of the harm may affect others who might not be able to ask a court for relief. In the United States, this is the grounds for asking for a law to be struck down as violating the First Amendment, because while the plaintiff might not be directly affected, the law might so adversely affect others that one might never know what was not done or created by those who fear they would become subject to the law – the so-called "chilling effects" doctrine.
- The party is granted automatic standing by act of law. Under some environmental laws in the United States, a party may sue someone causing pollution to certain waterways without a federal permit, even if the party suing is not harmed by the pollution being generated. The law allows them to receive a portion of any fines collected by the government from their violation of law. In some U.S. states, a person who believes a book, film or other work of art is obscene may sue in their own name to have the work banned directly without having to ask a District Attorney to do so.
In the United States, the current doctrine is that a person cannot bring a suit challenging the constitutionality of a law unless the plaintiff can demonstrate that the plaintiff is (or will imminently be) harmed by the law. Otherwise, the court will rule that the plaintiff "lacks standing" to bring the suit, and will dismiss the case without considering the merits of the claim of unconstitutionality. To have a court declare a law unconstitutional, there must be a valid reason for the lawsuit. The party suing must have something to lose in order to sue unless it has automatic standing by action of law.
International Courts 
In Canadian administrative law, whether an individual has standing to bring an application for judicial review, or an appeal from the decision of a tribunal, is governed by the language of the particular statute under which the application or the appeal is brought. Some statutes provide for a narrow right of standing while others provide for a broader right of standing.
Frequently a litigant wishes to bring a civil action for a declaratory judgment against a public body or official. This is considered an aspect of administrative law, sometimes with a constitutional dimension, as when the litigant seeks to have legislation declared unconstitutional.
Public interest standing 
The Supreme Court of Canada developed the concept of public interest standing in three constitutional cases commonly called "the Standing trilogy": Thorson v. Canada (Attorney General), Nova Scotia Board of Censors v. McNeil, and Minister of Justice v. Borowski. The trilogy was summarized as follows in Canadian Council of Churches v. Canada (Minister of Employment and Immigration):
It has been seen that when public interest standing is sought, consideration must be given to three aspects. First, is there a serious issue raised as to the invalidity of legislation in question? Second, has it been established that the plaintiff is directly affected by the legislation or if not does the plaintiff have a genuine interest in its validity? Third, is there another reasonable and effective way to bring the issue before the court?
Public-interest standing is also available in non-constitutional cases, as the Court found in Finlay v. Canada (Minister of Finance).
United Kingdom 
In British administrative law, the applicant needs to have a sufficient interest in the matter to which the application relates. This sufficient interest requirement has been construed liberally by the courts. As Lord Diplock put it:
"[i]t would...be a grave lacuna in our system of public law if a pressure group...or even a single public spirited taxpayer, were prevented by outdated technical rules of locus standi from bringing the matter to the attention of the court to vindicate the rule of law and get the unlawful conduct stopped."
United States 
In United States law, the Supreme Court of the United States has stated, "In essence the question of standing is whether the litigant is entitled to have the court decide the merits of the dispute or of particular issues."
There are a number of requirements that a plaintiff must establish to have standing before a federal court. Some are based on the case or controversy requirement of the judicial power of Article Three of the United States Constitution, § 2, cl.1. As stated there, "The Judicial Power shall extend to all Cases . . .[and] to Controversies . . ." The requirement that a plaintiff have standing to sue is a limit on the role of the judiciary and the law of Article III standing is built on the idea of separation of powers. Federal courts may exercise power only "in the last resort, and as a necessity".
The American doctrine of standing is assumed as having begun with the case of Frothingham v. Mellon, 262 U.S. 447 (1923). But legal standing truly rests its first prudential origins in Fairchild v. Hughes, (1922) which was authored by Justice Brandeis. In Fairchild, a citizen sued the Secretary of State and the Attorney General to challenge the procedures by which the Nineteenth Amendment was ratified. Prior to it the doctrine was that all persons had a right to pursue a private prosecution of a public right. Since then the doctrine has been embedded in judicial rules and some statutes.
In 2011, in Bond v. United States, the U.S. Supreme Court held a criminal defendant has standing to challenge the federal statute that he or she is charged with violating as being unconstitutional under the Tenth Amendment.
Standing requirements 
There are three standing requirements:
- Injury: The plaintiff must have suffered or imminently will suffer injury—an invasion of a legally protected interest that is concrete and particularized. The injury must be actual or imminent, distinct and palpable, not abstract. This injury could be economic as well as non-economic.
- Causation: There must be a causal connection between the injury and the conduct complained of, so that the injury is fairly traceable to the challenged action of the defendant and not the result of the independent action of some third party who is not before the court.
- Redressability: It must be likely, as opposed to merely speculative, that a favorable court decision will redress the injury.
Prudential limitations 
Additionally, there are three major prudential (judicially created) standing principles. Congress can override these principles via statute:
- Prohibition of Third-party standing: A party may only assert his or her own rights and cannot raise the claims of a third party who is not before the court; exceptions exist where the third party has interchangeable economic interests with the injured party, or a person unprotected by a particular law sues to challenge the oversweeping of the law into the rights of others. For example, a party suing over a law prohibiting certain types of visual material, may sue because the 1st Amendment rights of theirs, and others engaged in similar displays, might be damaged.
Additionally, third parties who do not have standing may be able to sue under the next friend doctrine if the third party is an infant, mentally handicapped, or not a party to a contract. One example of a statutory exception to the prohibition of third party standing exists in the qui tam provision of the Civil False Claims Act.
- Prohibition of generalized grievances: A plaintiff cannot sue if the injury is widely shared in an undifferentiated way with many people. For example, the general rule is that there is no federal taxpayer standing, as complaints about the spending of federal funds are too remote from the process of acquiring them. Such grievances are ordinarily more appropriately addressed in the representative branches.
- Zone of interest test: There are in fact two tests used by the United States Supreme Court for the zone of interest
Recent development of the doctrine 
In 1984, the Supreme Court reviewed and further outlined the standing requirements in a major ruling concerning the meaning of the three standing requirements of injury, causation, and redressability.
In the suit, parents of black public school children alleged that the Internal Revenue Service was not enforcing standards and procedures that would deny tax-exempt status to racially discriminatory private schools. The Court found that the plaintiffs did not have the standing necessary to bring suit. Although the Court established a significant injury for one of the claims, it found the causation of the injury (the nexus between the defendant’s actions and the plaintiff’s injuries) to be too attenuated. "The injury alleged was not fairly traceable to the Government conduct respondents challenge as unlawful".
In another major standing case, Lujan v. Defenders of Wildlife, 504 U.S. 555 (1992), the Supreme Court elaborated on the redressability requirement for standing. The case involved a challenge to a rule promulgated by the Secretary of the Interior interpreting §7 of the Endangered Species Act of 1973 (ESA). The rule rendered §7 of the ESA applicable only to actions within the United States or on the high seas. The Court found that the plaintiffs did not have the standing necessary to bring suit, because no injury had been established. The injury claimed by the plaintiffs was that damage would be caused to certain species of animals and that this in turn injures the plaintiffs by the reduced likelihood that the plaintiffs would see the species in the future. The court insisted though that the plaintiffs had to show how damage to the species would produce imminent injury to the plaintiffs. The Court found that the plaintiffs did not sustain this burden of proof. "The 'injury in fact' test requires more than an injury to a cognizable interest. It requires that the party seeking review be himself among the injured". The injury must be imminent and not hypothetical.
Beyond failing to show injury, the Court found that the plaintiffs failed to demonstrate the standing requirement of redressability. The Court pointed out that the respondents chose to challenge a more generalized level of Government action, "the invalidation of which would affect all overseas projects". This programmatic approach has "obvious difficulties insofar as proof of causation or redressability is concerned".
In a 2000 case, Vermont Agency of Natural Resources v. United States ex rel. Stevens, 529 U.S. 765 (2000), the United States Supreme Court endorsed the "partial assignment" approach to qui tam relator standing to sue under the False Claims Act — allowing private individuals to sue on behalf of the U.S. government for injuries suffered solely by the government.
Taxpayer standing 
The initial case that established the doctrine of standing, Frothingham v. Mellon, was a taxpayer standing case.
Taxpayer standing is the concept that any person who pays taxes should have standing to file a lawsuit against the taxing body if that body allocates funds in a way that the taxpayer feels is improper. The United States Supreme Court has held that taxpayer standing is not by itself a sufficient basis for standing against the United States government, unless the narrower Flast test is met. The Court has consistently found that the conduct of the federal government is too far removed from individual taxpayer returns for any injury to the taxpayer to be traced to the use of tax revenues, e.g., United States v. Richardson.
In DaimlerChrysler Corp. v. Cuno, the Court extended this analysis to state governments as well. However, the Supreme Court has also held that taxpayer standing is constitutionally sufficient to sue a municipal government in a federal court.
States are also protected against lawsuits by their sovereign immunity. Even where states waive their sovereign immunity, they may nonetheless have their own rules limiting standing against simple taxpayer standing against the state. Furthermore, states have the power to determine what will constitute standing for a litigant to be heard in a state court, and may deny access to the courts premised on taxpayer standing alone.
In Florida, a taxpayer has standing to sue if the state government is acting unconstitutionally with respect to public funds, or if government action is causing some special injury to the taxpayer that is not shared by taxpayers in general. In Virginia, the Supreme Court of Virginia has more or less adopted a similar rule. An individual taxpayer generally has standing to challenge an act of a city or county where they live, but does not have general standing to challenge state expenditures.
Standing to challenge statutes 
With limited exceptions, a party cannot have standing to challenge the constitutionality of a statute unless they will be subjected to the provisions of that statute. There are some exceptions, however, e.g. courts will accept First Amendment challenges to a statute on overbreadth grounds, where a person who is only partially affected by a statute can challenge parts that do not affect them on the grounds that laws that restrict speech have a chilling effect on other people's right to free speech.
The only other way someone can have standing to challenge the constitutionality of a statute is if the existence of the statute would otherwise deprive them of a right or a privilege even if the statute itself would not apply to them. The Virginia Supreme Court made this point clear in the case of Martin v. Ziherl 607 S.E.2d 367 (Va. 2005). Martin and Ziherl were girlfriend and boyfriend and engaged in unprotected sexual intercourse when Martin discovered that Ziherl had infected her with herpes, even though he knew he was infected and did not inform her of this. She sued him for damages, but because (at the time the case was filed) it was illegal to commit "fornication" (extramarital sexual intercourse), Ziherl argued that Martin could not sue him because joint tortfeasors - those involved in committing a crime - cannot sue each other over acts occurring as a result of a criminal act (Zysk v. Zysk, 404 S.E.2d 721 (Va. 1990)). Martin argued in rebuttal that because of the U.S. Supreme Court decision in Lawrence v. Texas (finding that state's sodomy law unconstitutional), Virginia's anti-fornication law was also unconstitutional for the reasons cited in Lawrence. Martin argued, therefore, she could, in fact, sue Ziherl for damages.
Lower courts decided that because the Commonwealth's Attorney doesn't prosecute fornication cases and no one had been prosecuted for fornication anywhere in Virginia in over 100 years, Martin had no risk of prosecution and thus lacked standing to challenge the statute. Martin appealed. Since Martin has something to lose - the ability to sue Ziherl for damages - if the statute is upheld, she had standing to challenge the constitutionality of the statute even though the possibility of her being prosecuted for violating it was zero. And since the U.S. Supreme Court in Lawrence has found that there is a privacy right in one's private, noncommercial sexual practices, the Virginia Supreme Court decided that the statute against fornication was unconstitutional. The finding gave Martin standing to sue Ziherl since the decision in Zysk is no longer applicable.
However, the only reason Martin had standing to challenge the statute was that she had something to lose if it stayed on the books.
State law 
State law on standing differs substantially from federal law and varies considerably from state to state.
On December 29, 2009, the California Court of Appeal for the Sixth District ruled that California Code of Civil Procedure Section 367 cannot be read as imposing a federal-style standing doctrine on California's code pleading system of civil procedure. In California, the fundamental inquiry is always whether the plaintiff has sufficiently pleaded a cause of action, not whether the plaintiff has some entitlement to judicial action separate from proof of the substantive merits of the claim advanced. The court acknowledged that the word "standing" is often sloppily used to refer to what is really jus tertii, and held that jus tertii in state law is not the same thing as the federal standing doctrine.
See also 
- Smith, Rhona K. M., Textbook on International Human Rights. 4th Edition. 2010.
- For example, under s. 18(1) the Federal Court Act, an application for review may be made by "anyone directly affected by the matter in respect of which the relief is sought".
- Thorson v. Canada (Attorney General),  1 S.C.R. 138.
- Nova Scotia Board of Censors v. McNeil,  2 S.C.R. 265.
- Minister of Justice v. Borowski,  2 S.C.R. 575.
- Canadian Council of Churches v. Canada (Minister of Employment and Immigration),  1 S.C.R. 236
- Finlay v. Canada (Minister of Finance),  2 S.C.R. 607 .
- Supreme Court Act 1981 s.31(3).
- Inland Revenue Commissioners Appellants v National Federation of Self-Employed and Small Businesses Ltd. Respondents  A.C. 617.
- Warth v. Seldin, 422 U.S. 490, 498 (1975).
- Allen v. Wright, 468 U.S. 737, 752 (1984).
- Allen v. Wright, 468 U.S. 752 (1984).
- The Metaphor of Standing and the Problem of Self-Governance, by Steven L. Winter, 40 Stan. L. Rev. 1371, July, 1988.
- For example, Massachusetts v. Environmental Protection Agency (global warming caused by EPA's refusal to regulate carbon dioxide emissions satisfied element of causation for Massachusetts's alleged injury of loss of coastland).
- Lujan v. Defenders of Wildlife, 504 U.S. 555 (1992).
- Vermont Agency of Natural Resources v. United States ex rel. Stevens, 529 U.S. 765 (2000)
- Federal Election Commission v. Akins, 524 U.S. 11 (1998).
- Allen v. Wright, 468 U.S. 737 (1984).
- Allen v. Wright, 468 U.S. at 752 (1984).
- Allen v. Wright, 468 U.S. at 755 (1984).
- Allen v. Wright, 468 U.S. at 757 (1984).
- Lujan v. Defenders of Wildlife, 504 U.S. at 562.
- Lujan v. Defenders of Wildlife, 504 U.S. at 564.
- Lujan v. Defenders of Wildlife, 504 U.S. at 563.
- Lujan v. Defenders of Wildlife, 504 U.S. at 568.
- Text of Vermont Agency of Natural Resources v. United States ex rel. Stevens
- Nathan D. Sturycz, The King and I?: An Examination of the Interest Qui Tam Relators Represent and the Implications for Future False Claims Act Litigation, 28 St. Louis Pub. L. Rev. 459 (2009), available at http://papers.ssrn.com/sol3/papers.cfm?abstract_id=1537749. For the general standing rule, Lujan v. Defenders of Wildlife, 504 U.S. 555 (1992)
- Flast v. Cohen, 392 U.S. 83 (1968).
- 547 U.S. 332 (2006).
- Jasmine Networks, Inc. v. Superior Court (Marvell Semiconductor, Inc.), 180 Cal. App. 4th 980 (2009).