What Counts as “Public Interest”? The Legal Justification Everyone Invokes
Politicians use it. Journalists rely on it. Lawyers argue it. Yet few can clearly define it. The phrase “public interest” is one of the most powerful and flexible concepts in modern law. This article explores how courts across the world decide when serving the public interest justifies breaching privacy, secrecy, or even established rights.
Few legal terms carry as much moral authority as “public interest.” It appears in constitutions, statutes, and case law from London to Lagos, usually invoked to justify something controversial. Governments use it to defend surveillance or data collection. Media lawyers cite it to justify publishing leaked information. Regulators rely on it to balance competing rights.
The trouble is that “public interest” is not one fixed idea. It is a moving target that shifts depending on who defines “the public” and what counts as their “interest.” The concept sits somewhere between ethics, policy, and law — vague enough to invite debate, but strong enough to decide cases.
A balancing act, not a free pass
In most democracies, the public interest does not operate as a blank cheque. It functions as a balancing mechanism between rights that clash. The most obvious example is the tension between privacy and free expression.
In the United Kingdom, the Human Rights Act 1998 requires courts to weigh Article 8 (the right to private life) against Article 10 (the right to freedom of expression). In cases like Campbell v MGN (2004), involving supermodel Naomi Campbell’s treatment for addiction, the court held that publishing details of medical care was not justified by public interest, even if the story itself had some.
By contrast, in Reynolds v Times Newspapers (1999), the House of Lords carved out what became known as the “Reynolds defence,” allowing journalists to publish potentially defamatory material if they could show it was responsible reporting on a matter of public concern. That balance later evolved into the Defamation Act 2013, which protects publications that can be shown to serve the public interest and were reasonably verified before publication.
When the state claims it
Governments frequently invoke the public interest to limit access to information or justify exceptional powers. National security is the most common example. Freedom of information laws in the UK, Canada, and Australia all contain “public interest exemptions” that allow officials to withhold documents if disclosure would harm national safety or diplomatic relations.
Yet these exemptions are not absolute. In the UK, the Information Commissioner’s Office often orders disclosure when the public benefit of transparency outweighs the potential harm. Courts have echoed this logic in surveillance cases, recognising that even legitimate state interests must be balanced against the rights of individuals.
The pattern is similar elsewhere. In the United States, the Freedom of Information Act (FOIA) allows withholding certain records, but it also recognises a strong presumption in favor of disclosure. Public interest in accountability can override bureaucratic instinct for secrecy.
When the media claims it
For journalists, the public interest is both shield and sword. It protects publications that might otherwise breach confidentiality, defamation, or data protection law. The European Court of Human Rights has repeatedly affirmed that investigative journalism plays a watchdog role essential to democracy.
In Axel Springer AG v Germany (2012), the Court held that reporting on a celebrity’s arrest was justified because it contributed to a debate of public interest about criminal justice, not simply gossip. Conversely, in Von Hannover v Germany (No 2) (2012), photographs of Princess Caroline on holiday were ruled outside the public interest because they did not inform any public debate.
The distinction is subtle but important. Curiosity about the powerful is not the same as scrutiny of power itself. The law protects the latter.
When business invokes it
Corporations and regulators also use the public interest to justify market interventions. Competition authorities argue that blocking a merger serves the public interest if it prevents consumer harm. Environmental agencies rely on it when imposing restrictions that limit private enterprise for collective good.
In recent years, the concept has migrated into data protection. Under the UK GDPR, certain forms of data processing are lawful if they are “necessary for the performance of a task carried out in the public interest.” That includes statistical research, health monitoring, and certain forms of journalism. But again, necessity and proportionality are key. The public interest must be specific, not speculative.
A flexible principle across borders
Different legal cultures treat the idea with different levels of skepticism. In the United States, the First Amendment creates a strong presumption in favor of publication, leaving the public interest test mainly for national security or whistleblower cases. In continental Europe, where privacy rights carry more weight, the concept functions as a narrow exception that must be proven rather than assumed.
In common law systems, the test has evolved through case law rather than statute. Judges often ask: Does the disclosure contribute to a matter of genuine public concern? Was the information verified and necessary? Were less intrusive means available? These practical questions turn an abstract ideal into a workable rule.
The danger of overuse
Because the phrase sounds virtuous, it can be misused. Governments sometimes stretch “public interest” to justify secrecy, censorship, or even corruption under the banner of protection. Corporations invoke it to resist scrutiny, while campaigners claim it to demand transparency at any cost.
The danger lies in treating the public interest as an objective truth when it is, in fact, a contestable judgment. What benefits one group might harm another. A journalist’s exposé may inform the public but ruin private lives. A government leak might reveal misconduct but jeopardise national security. The law exists to mediate these tensions, not erase them.
The future of public interest
Digital platforms have complicated the picture further. When every citizen can publish, who decides what counts as journalism and what counts as gossip? Algorithms amplify outrage, not nuance, yet the same legal tests still apply. Courts increasingly consider reach and motive: was the purpose of publication to inform, or simply to provoke?
Artificial intelligence will deepen these questions. If AI tools compile and share sensitive data for “research in the public interest,” how should consent, privacy, and accountability be handled? Policymakers are only beginning to grapple with the answers.
The public interest is not a single value but a negotiation between rights. It is the principle that keeps law dynamic - forcing courts to balance transparency against privacy, security against accountability, and freedom against responsibility.
Its strength lies in its flexibility, but that is also its risk. Used wisely, the public interest defends democracy and exposes abuse. Used carelessly, it becomes a slogan that justifies almost anything. The challenge for lawyers, journalists, and policymakers alike is to keep asking the hardest question of all: whose interest, exactly, is being served?
The Legal Integrity Project Editorial Team