The term is widely used to refer to more esoteric entities in a
number of disciplines, including - philosophy, when a concept is
not available[clarification needed] - biology when a species
does not fit into a genus which includes other species - law
when a special and unique interpretation of a case or authority
is found to be necessary - town planning where there is no
existing use case[clarification needed] - intellectual property
rights where there is no defining characteristic[clarification
needed]; and - politics and societal norms where there is no
real authority perceived[clarification needed]. The expression
is often used in analytic philosophy to indicate an idea, an
entity, or a reality which cannot be reduced to a lower concept
or included in a wider concept. In the taxonomical structure
"genus → species", a species is described as sui generis if its
genus was created to classify it (i.e. its uniqueness at the
time of classification merited the creation of a new genus, the
sole member of which was