The Competition Act 1991 represents a significant overhaul of Irish competition law, replacing outdated legislation with a comprehensive framework that aligns closely with EU principles. It shifts the focus from merely registering restrictive agreements to outright prohibiting anticompetitive behaviours. The Act introduces two main prohibitions: anticompetitive agreements, which include practices like price-fixing and market sharing, and the abuse of a dominant position, addressing exploitative and exclusionary tactics. Notably, agreements are void by default unless exempted, promoting a healthier competitive landscape.

Furthermore, the Act empowers the Competition Authority, now known as the Competition and Consumer Protection Commission, with robust investigatory powers, including conducting dawn raids and issuing advisory opinions. It modernises merger control through voluntary notification and fosters compliance and transparency in markets. This landmark legislation marks a pivotal shift in Irish economic regulation and sets the foundation for modern enforcement aligned with EU norms.