Legal Definitions - contagion

In international law, the term contagion refers to a historical and now widely rejected idea that a country is justified in invading a neighboring state and overthrowing its government if that neighbor is experiencing a revolution or engaging in practices deemed unacceptable. The invading country would claim this action is necessary to protect its own national security, fearing that the undesirable developments in the neighboring state could "spread" across its borders and destabilize its own society or political system.

This doctrine is considered discredited because it violates fundamental principles of international law, such as national sovereignty and non-interference in the internal affairs of other states.

• Example 1: Suppressing a Democratic Movement

  Imagine a powerful, authoritarian nation, "Veridia," shares a border with a smaller country, "Aethelgard." Aethelgard experiences a popular uprising, leading to the overthrow of its long-standing monarchy and the establishment of a new, democratically elected government. Veridia's authoritarian leaders, fearing that the success of democracy in Aethelgard could inspire similar movements among their own populace, invoke the doctrine of contagion. They declare that Aethelgard's democratic revolution poses an existential threat to Veridia's national security and stability. Consequently, Veridia launches a military invasion of Aethelgard, with the stated goal of restoring order and installing a government more aligned with Veridia's own political system.

  This illustrates contagion because Veridia justifies its invasion and interference in Aethelgard's internal affairs not based on a direct attack, but on the perceived "spread" of a political ideology (democracy) that it considers dangerous to its own regime.

• Example 2: Preventing Social Unrest Spillover

  Consider a prosperous nation, "Xylos," bordering a less developed country, "Zylos," which is experiencing severe economic collapse, widespread famine, and significant social unrest. Large numbers of Zylos's citizens are attempting to cross into Xylos as refugees, and there are reports of armed groups forming within Zylos. The government of Xylos, fearing that the chaos, refugee crisis, and potential for armed conflict could spill over its borders, destabilize its own economy, and strain its social services, decides to intervene militarily in Zylos. They claim this intervention is necessary to prevent the "contagion" of instability from Zylos from undermining Xylos's national security.

  This example demonstrates contagion as Xylos uses the internal instability and humanitarian crisis in Zylos as a pretext for military intervention, arguing that the "abhorrent practices" (in this case, widespread disorder and collapse) in the neighboring state directly threaten its own security and justify an invasion to control the situation.