| Abbreviation | Definition |
|---|---|
| IRSSA | Indian Residential Schools Settlement Agreement |
| IRT | Incident Response Team |
| IRU | Indefeasible Right of Use |
| ISAOA | Its Successors And/Or Assigns |
| ISB | Idaho State Bar |
| ISB | Illinois State Bar |
| ISB | Indiana State Bar |
| ISB | Iowa State Bar |
| ISBA | Illinois State Bar Association |
| ISBA | Indiana State Bar Association |
| ISBA | Iowa State Bar Association |
| ISC | International Supreme Council |
| ISCCP | Illinois Supreme Court Commission on Professionalism |
| ISCI | International State Crime Initiative |
| ISCJ | Institut de Sciences Criminelles et de la Justice |
| ISCL | Irish Society Of Comparative Law |
| ISCL | Italian Society for Construction Law |
| ISCL | Italian Society of Construction Law |
| ISCS | Imperial Sovereign Court of Spokane |
| ISIJ | International Science and Investigation journal |