Veto

A veto is a legal mechanism that allows an individual or institution—typically a head of state, executive authority, or designated political actor—to unilaterally block or halt an official action. Most commonly, a veto prevents a legislative bill from becoming law. Veto authority is deeply embedded in constitutional and political systems worldwide, functioning as a crucial instrument of checks and balances within government structures. While many vetoes may be overridden by a supermajority vote, others are absolute. The word derives from the Latin veto, meaning I forbid.

Forms and Distribution of Veto Power

Constitutions in many countries explicitly define veto powers, establishing how they may be exercised and whether they can be overturned. Presidential and semi-presidential systems typically include strong executive vetoes, whereas parliamentary systems often grant only ceremonial or very limited veto authority to heads of state. At sub-national levels—states, provinces, and municipalities—similar mechanisms exist. International bodies, most prominently the United Nations Security Council, also employ veto systems.
In the United States, the President may veto legislation, but Congress can override the veto with a two-thirds majority in both chambers. By contrast, the five permanent members of the UN Security Council—China, France, Russia, the United Kingdom, and the United States—hold an absolute veto, capable of blocking any substantive resolution regardless of majority opinion.
Some systems also permit executives to propose modifications to vetoed bills. For instance, an Indian president may return legislation with suggested amendments, an authority referred to as an amendatory veto.
While not all political systems embed formal vetoes, all contain what political theorists call veto players—individuals or groups with sufficient influence to prevent changes to policy.

Historical Development

Roman Origins

The earliest formalised veto power emerged in the Roman Republic. The intercessio empowered the tribunes of the plebs to protect the interests of non-patrician citizens by blocking actions of magistrates or decisions of the Senate. A tribune’s veto did not nullify Senate measures but denied them legal force.
Roman consuls likewise held mutual veto power: either consul could stop the other’s actions. The veto thus served not only to regulate state affairs but to limit excessive concentration of authority.
A notable episode occurred in 133 BC when Tiberius Gracchus proposed land reforms. When fellow tribune Marcus Octavius vetoed the proposal, the plebeian assembly removed him from office. Gracchus was later killed amid political upheaval, illustrating both the power and danger of veto politics.

Liberum Veto in Poland–Lithuania

In the Polish–Lithuanian Commonwealth of the 17th and 18th centuries, the liberum veto required unanimous consent in the Sejm. Any single legislator could dissolve the session and void all legislation passed therein. Although rooted in ideals of noble equality, the practice eventually paralysed governance and contributed to the Commonwealth’s eventual partitions.

Emergence of Modern Executive Vetoes

Modern veto systems stem partly from the evolution of royal assent procedures in Europe. Monarchs once held wide discretion to deny consent to proposed laws. Although the British monarch has not refused assent since 1708, colonial governors continued to exercise this power. Indeed, extensive use of royal vetoes in the American colonies was cited in the Declaration of Independence.
Following the French Revolution, the royal veto became a subject of fierce debate. The Constitution of 1791 granted King Louis XVI a suspensive veto, which could be overridden through successive legislative sessions. With the abolition of the monarchy in 1792, this provision lapsed.
In republican political thought of the 18th and 19th centuries, presidential vetoes were viewed as safeguards against majoritarian excess. Some thinkers, including Thomas Jefferson, opposed the veto as monarchical in nature. While early presidential constitutions often featured override mechanisms, others granted absolute vetoes; the Chilean Constitution of 1833 is an example.

Types of Vetoes

Vetoes can be categorised by who exercises them, their scope, and whether they may be overridden.

• Executive veto: exercised by a head of state or government.
• Legislative veto: historically used by legislatures to overturn executive actions.
• Judicial veto: the practical effect of judicial review when courts strike down legislation.

Vetoes may also serve specialised functions, such as protecting social groups—exemplified by the Roman tribunes’ veto—or safeguarding relations between levels of government, as with colonial governors.
Proposals for indigenous vetoes in resource development projects have gained prominence following the 2007 UN Declaration on the Rights of Indigenous Peoples, though many governments have resisted adopting legally binding consent requirements.

By Override Conditions

• Absolute veto: cannot be overridden.
• Qualified veto: may be overridden by a supermajority.
• Suspensive veto: delays but does not permanently block legislation; override typically requires only a simple majority.

Executive Veto Variants

Several forms of executive veto have evolved.

• Package veto: rejects an entire bill.
• Partial or line-item veto: rejects specific provisions while signing the rest into law, often used in budgetary legislation.
• Amendatory veto: returns a bill with suggested changes. Depending on the system, legislative inaction may cause either the bill or the veto to prevail.
• Reduction veto: allows reduction of appropriations, common in some US states.
• Policy veto: applies to any subject matter, as opposed to vetoes restricted to budgetary or constitutional issues.