Duhaime's Law Dictionary

Sui Generis Definition:

Latin: of its own kind.

Something which is distinct and forms a unique class; the only one of its kind- one of a kind; without parallel.

A contract or legal right that may resemble other, similar rights but which has a fundamental distinct feature which ought not to be grouped with others.

For example, in wrestling with the legal status of an aged treaty between the First Nations of North America and European settlers, Canada's Supreme Court mused that a:

"... treaty with the Indians is unique, that it is an agreement sui generis which is neither created nor terminated according to the rules of international law."1

In order to dispose of a case put before it as stare decisis, a court may state that the proposed case is sui generis and thus not applicable under the principles of stare decisis.


  • R v Sioui, [1990] 1 S.C.R. 1025; also at 70 D.L.R. (4th) 427; 56 C.C.C. (3d) 225 and [1990] 3 C.N.L.R. 127 (note 1)

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