What defines a serious agreement to commit an unlawful act?

A serious agreement to commit an unlawful act is best defined as conspiracy. Conspiracy involves two or more individuals planning to engage in illegal activity, establishing a clear intent and agreement to carry out that plan. The essence of conspiracy is the collaboration towards a common unlawful goal, which is what distinguishes it from other legal concepts.

Collusion, while it also involves cooperation between parties, typically refers to secret or illegal cooperation, often in the context of business dealings or competitive disadvantages, rather than simply agreeing to commit an unlawful act. Contravention is about violating a law or regulation but does not involve an agreement between parties. Conformity refers to adherence to rules, standards, or laws and does not imply any unlawful intent. Therefore, conspiracy directly identifies the core element of an agreement geared towards unlawful actions.