Sui generis
A similar case that led to the use of the label "sui generis" is the relationship of New Caledonia relative to France, because the legal status of New Caledonia can aptly be said to lie somewhere between a French overseas collectivity and a sovereign nation. Although other examples of such status for other dependent or disputed territories may exist, this arrangement is unique within the French realm.
Sui generis
For example, in road traffic law, a statute may require consideration of large vehicles separately from other vehicles. The word "large" is ambiguous per se, but may be considered "heavy". Thus the relevant legislation (in Australian law) contains a section called "Terms used" or "Definitions" that itemises all words considered ambiguous, and confers specific interpretations consistent with natural language. So, this list tells us that "heavy vehicle" means a vehicle with a "GVM" over 4.5 tons;" and "GVM" means "gross vehicle mass"—the maximum loaded mass of the vehicle. Further explanations cover various contingencies. Thus "large" is equivalent to "heavy" and is (for this unique case) clearly defined, "sui generis".