sui generis

Definition from Nolo’s Plain-English Law Dictionary

(soo-ee jen-ris) Latin for of its own kind, and used to describe a form of legal protection that exists outside typical legal protections -- that is, something that is unique or different. In intellectual property law, for example, ship hull designs have achieved a unique category of protection and are "sui generis" within copyright law.

Definition provided by Nolo’s Plain-English Law Dictionary.