Courts, juries, lawyers, Law enforcement, justice, but also the legislative process.

Law refers to the body of binding rules and principles recognized by a community: statutes, case law or regulations. These are prescribed and enforced by a controlling authority, which makes them binding and subject to penalties or negative consequences if not followed (Black’s Law Dictionary, 6th ed.).
A legal system is the institutional framework or controlling authorities through which those rules are created, interpreted, and applied: courts, legislatures, enforcement bodies. Black’s Law Dictionary (2nd Ed) describes the legal system via the jurisdiction’s components, such as: its constitution (written or oral), its legislation (primary and subsidiary/bylaws), or traditional practices accepted by courts.

External posts:
Book Review: Legal Systems Very Different From Ours
Legal Systems Very Different From Ours, Because I Just Made Them Up
Slightly Skew Systems Of Government
A Comprehensive Reboot of Law Enforcement

Related tags: Government, Mechanism Design