Final answer:
The social institution that includes lawyers' associations, courts, and jails is the law, which comprises formal organizations governing legal interactions and practices.
Step-by-step explanation:
The social institution of the law would include groups or organizations such as lawyers' associations, courts, and jails. These elements are integral components of the legal system, which is a formal institution with a set of rules and practices dictating how members (such as lawyers, judges, and citizens) interact with one another within a governed society. For example, to practice law individuals are often required to join professional organizations like the American Bar Association or a state bar association. Jails, as part of the penal system, serve to detain those who have been convicted of crimes, thus enforcing legal codes.