states' rights vs plural

states' rights and plural both are nouns.

Word	Noun	Adjective	Verb	Adverb
states' rights	Yes	No	No	No
plural	Yes	Yes	No	No

states' rights (noun)	plural (noun)
the rights conceded to the states by the United States constitution	the form of a word that is used to denote more than one
a doctrine that federal powers should be curtailed and returned to the individual states

states' rights (adjective)	plural (adjective)
	grammatical number category referring to two or more items or units
	composed of more than one member, set, or kind